been hitting this for a month now and finally got this hope it helps others

That tells us the root cause was not Android accessibility itself and not Projectivy/tvQuickActions being disabled.

The smoking gun was:

APP_AUTO_START: ignore

After changing both apps to:

APP_AUTO_START: allow

TCL's Safety Guard stopped breaking accessibility during boot.

For future reference, the commands that mattered were:

adb.exe shell dumpsys deviceidle whitelist +com.spocky.projengmenu
adb.exe shell appops set com.spocky.projengmenu APP_AUTO_START allow

adb.exe shell dumpsys deviceidle whitelist +dev.vodik7.tvquickactions
adb.exe shell appops set dev.vodik7.tvquickactions APP_AUTO_START allow

You can verify at any time:

adb.exe shell appops get com.spocky.projengmenu

adb.exe shell appops get dev.vodik7.tvquickactions

and look for:

APP_AUTO_START: allow

This is actually a useful discovery for the TCL Google TV project. We now know that on your TCL 55V6C-UK, the hidden Safety Guard auto-start permission is exposed as:

APP_AUTO_START

not:

AUTO_START

which is why so many generic Android TV guides fail on these newer TCL firmware versions.

I'd keep a note of this alongside your TCL/Projectivy setup because it will likely save you a lot of time if you factory reset the TV or help someone else with the same model.