Everything is AOSP-based including Talkback. It would appear that Subsystem Screenreader is a fork of the Talkback from AOSP/the Github repository. It's probably the most responsive I've ever seen Talkback in an Android emulator, not to mention one of the most responsive emulators I've seen - Intel Bridge is definitely to thank for that. Things to know regarding Talkback:
1. No alt+space to open the global context menu for Talkback (making an alternate command for that should've been a no brainer). To access Talkback settings, or any other settings in general:
A. Enable develoepr mode in the subsystem.
B. Copy the vm's ip address.
C. In a command line:
adb connect ip.add.re.ss:5555
adb -s ip.add.re.ss shell
am start -n com.android.settings/com.android.settings.Settings
Then you can access the regular Android system settings (the system settings are not vailable as an app in your start menu or through the subsystem manager itself..
2. The TTS appears to be a bridge to the onecore speech framework. There is, at present, no way to change this in the screenreader itself. I say this because the subsystem clearly recognizes other tts engines as it plays their respective samples, so why they went this route with the screenreader I'm not sure. Part of me wants to install the Android Accessibility Suite, but that would most definitely ruin the ctrl+win+t shortcut.
I'm going to be very frank. This thing is probably going to only appeal to developers and maybe video gamers if nothing else, simply because they chose to play ball with Amazon rather than go a little harder at convincing Google of the potential. Not everyone is going to know how to sideload apps, and even then the subsystem is not rooted, so installing gms is kind of impossible with the read only .img.
Other than that, this has got to be the most lean-built Android emulator better than anyone on the market, commercial or otherwise, and I'm really impressed with how smooth this damn thing runs for a beta.