Develop Reference

Is there an API to programmatically configure or start focus mode on Android

Android 10 introduced Focus Mode that can be used to temporarily block certain apps. I was wondering if there is an official android API to configure and/or turn on Focus Mode. I searched the forums and also checked the Android developers website but I could not find anything for this.

No, there isn't an official API yet to develop for Focus Mode. Currently, it is only available as a feature to end users. Fingers crossed to get this API at this year's I/O maybe.

Does Device admin deprecation means that we will no longer be able to disable camera?

As Android Device Administration is going to be deprecated. It will be replaced with Android Enterprise Mobility Manager(EMM), and as shown in the feature list disabling of camera is not supported in work profile. Work managed device would require a factory reset in order to setup.
So will we no longer be able to disable cameras for BYOD? Or are there other methods to disable camera for all profiles/entire device like Samsung KNOX does?

yes the API will be deprecated but your app will not break if you are targeting older version of Android e.g.
targetSdkVersion 25

Work profile is not a solution as it will disable camera only for apps under this profile and not for personal apps.
You should use the legacy mode with old sdk and Google may prevent you to publish updates at Play store.
I think that BYOD will be a real issue at Android 10.

Is the Sony Android camera API supported for all Android versions?

I'm wondering if the Sony Camera API has parts that are only supported by certain versions of Android.
I have the latest firmware (1.04) on my a6500 and running Android 7 on LineageOS (successor of CyanogenMod) for the Samsung S5 (KLTE version). This is what I get in my Play Memories app:
The shutter button works and images download to the phone. But that's it.
Additionally, when I use another app called DSLRDashboard, the settings show up and can be changed on the app, but they don't get changed or applied on the camera, and this is in full manual mode on the camera. Other modes don't work either.
What could be causing this? What would need to be added into a 3rd party ROM like LineageOS to get this working?
Really hoping that the official Sony developers that roam this site will be able to chime in.

So, a bit of a snafu on my part.
It's not enough to update just the firmware on the Sony camera. The Remote Control app installed in the camera must also be updated as well, which means hooking the camera up to WiFi and downloading the updates for that app. With that done, all the settings appear in the phone app and can the changed.

Mobile Device Managed Single App Devices

I like to have single android app in our managed devices, we want only that app to be used on the device with necessary restriction, such that,
Single use - Device will have only one app, user can't use other apps, like browsing, youtube or anything,
the initial setting like notification sound, GPS always on, notification and ring sound maximum level can't be modified.
user can not power off the device.
this setting can only be changed by our servers.
i think i have 2 option,
1) Using samsung knox sdk on samsung devices,
Here's MDM proving feature of Samsung Knox Standard!
2) General Android way, Set up Single-Purpose Devices, COSU solution
Android Developer's site.
Wanted to know your's view on this, may be if you guys have done any of the two or any other ways, i could use some of the guidelines or a path.
Thanks for reading, and please comment if i was unable to articulate the subject or it needs editing.

You can use Google's new Android Management API, it seems to suit your needs.
It is a new cloud API that allows to manage Android devices from a server, without having to build an on-device agent (a device policy controller).

I have broad experience of using Samsung Kiosk Mode from Knox Standard SDK which is free and Pro-Kiosk mode from Knox Customization SDK (which has more functions but is not free).
So I can tell you for sure that all 4 points that you have mentioned can be achieved by using Knox Standard SDK.
Singe Purpose: https://seap.samsung.com/api-references/android-standard/reference/android/app/enterprise/kioskmode/KioskMode.html
LocationPolicy (you can turn on GPS and restrict changing): https://seap.samsung.com/api-references/android-standard/reference/android/app/enterprise/LocationPolicy.html
Yes. It is possible but I forgot the exact implementation.
Yes, as well.
Only downside of using this SDK is:
You are tied to Samsung (which I personally okay with, since Samsung has such market penetration and you could get service almost anywhere in the world and in enterprise world it is critical)
About Android native functionality: never tried it
Update March 7, 2019: Now I am playing around Device Owner, we use it for Kiosk mode, works well and works on android Device with Nougat and earlier.

Hardware capabilities and actual implementation of Android API of a device

Up to now I was only developing in J2ME and would like to know about the differences compared to Android.
The situation for a java enabled phone is that it might, for example, has a built-in camera, but the manufacturer didn't implemented the Java API for camera capabilities. Which means you can't use that API. It is even possible that only parts of an API were implemented.
Now, what about Android? For what I know, when a device has Android Platform 2.2 it supports every API Level up to Level 8. And I would guess, that if the built in camera doesn't have a flash then you can't use the Android API call to change the flash mode. Is that right?
Now let's assume that the device has a built in flash enabled camera. Can a developer be sure that the function for changing the flash mode can be used, or is it possible that the manufacturer didn't implemented that specific function even though it is part of the supported API Level which the device was advertised for?

And I would guess, that if the built in camera doesn't have a flash then you can't use the Android API call to change the flash mode. Is that right?
So long as you set it to a valid value, you can always use the API. However, in your case, there is probably only one valid value (i.e., no flash).
Now let's assume that the device has a built in flash enabled camera. Can a developer be sure that the function for changing the flash mode can be used, or is it possible that the manufacturer didn't implemented that specific function even though it is part of the supported API Level which the device was advertised for?
Android devices that do not have the Android Market have no guarantees whatsoever regarding their compatibility with third-party apps.
Android devices that do have the Android Market must pass a compatibility test suite. Whether or not that test suite has a specific test for a specific API can only be determined by looking at the test suite code.
So, it depends on how you define "sure". Developers usually don't have to worry about it, but device firmware bugs do happen.