Maybe you should take a look at https://unbox.at/ it is anon addy in background but selfhosted from the German adminforge.de service. I use it myself for discord and until now the domain is Working.

Me to, but keep up with the kuketz blog he knows what he talks about.

Mike Kuketz, has created an article for best Android apps for graphene OS. It is in Herman, but maybe it helps.

https://www.kuketz-blog.de/empfehlungsecke/#android

Na Linux, was sonst. :)