While doing exploration on a larger article I’m currently writing, I realized that my FOSS (Free and Open Source Software) Android ways prevented me from using most Google services. I thought this also meant Talkback, the only AT (Assistive Technology) for Android.
The only other snag I hit was that no Text-to-Speech engine comes installed. A quick look online led me to a FOSS option that’s a bit outdated called Flite TTS on F-Droid.
Worked like a charm, and a mostly FOSS Talkback for Android is up and running. Hope this helps you out!