Been using it for years on grapheneos. Runs afaik via https only, super lightweight clientside

I have been using Hauk for ages. Not the most advanced or modern, but works like a charm! https://github.com/bilde2910/Hauk

Graphene runs on Google hardware… So deapite getting rid of google, you will unfortunately still have to hand them a load of money.

As far as what device to pick… https://grapheneos.org/faq#device-support

I used to use a pixel 7, recently upgraded to a 9. In the EU on vodafone no issues with anything. Also not when travelling outside of europe.