I like Thunder and Eternity
EpicVision
Yes. Check out this list: https://privsec.dev/posts/android/banking-applications-compatibility-with-grapheneos
GrapheneOS is amazing
Yeah Vultr is great
As far as I can see on their website, they don't mention end to end encryption or zero-knowledge encryption. If that is true, it means that they are able to read all your emails (and so can the government if they order them to reveal the data). They sometimes use some pretty confusing marketing slag in general. It's misleading because they advertise things like in-transit TLS encryption, which is standard nowadays. Even Gmail, Outlook, iCloud, Yahoo and other mainstream email providers have this by default. This is nothing special and they hope that people think it means the same as E2EE. If you care about data ownership, you should also care about (end-to-end) encryption. Only when you are the only key holder, you can be sure that no one can access your private stuff.
Sure, you go ahead and try it out for yourself to see if it works. Just wanted to let you know that selfhosting an Email server is not easy. Regarding ethics, I like Proton because they support privacy, open source software, and they never sold out to VC. Their website is accessible via Tor, they accept Bitcoin payments and they actually care about their users. That's probably the most ethical email provider you can find.
a bit? It's not just a bit overkill, this is absolutely brain dead.
But it's not completely dead yet, it's just slowly dying.