I have a phone to experiment.
What linux should I try to install?
I'm also looking for a good tutorial to do this.

I've been saying for years there should be a database for mobile devices and available OSs.
Unfortunately I have not found it yet.
So you're going to have to start looking at various alternative OSs, and see which devices they support.
Start with LineageOS, Ubuntu Touch, PostmarketOS and Replicant etc.
Also look at all the OSs that have releases for the Pinephone and see if one of them also supports your device.

Not a direct answer, but: I have changed my approach. I find a mobile OS that interests me, then I go out to buy a supported device. Cheaply. My current devices cost me between 30€ and 60€.