trackd

No

Yep, i did miss that but have updated my comment

Its permissions for fullscreen notifications, i dont think many apps send ads that way. They can just show them fullscreen when your using the app.

~~Probably all apps that has some voip calling functionality.~~

~~Whatsapp, messenger, viber (is that still a thing?) and similar~~

Edit, just saw

Unless they provide call or alarm functionality

So they should be safe

Possibly some security related apps to auth for banking and stuff, not sure how they work behind the scenes.

Same goes for some 2FA apps i guess?

Found this issue

I would probably just setup temporary containers or something instead.

As for your firefox issues, thats pretty trivial to fix by adding some CSS in usercontent.css/userchrome.css

See here for some examples: MrOtherGuy/firefox-csshacks