Actually, why write the guide for PGP key generation with Enigmail and integration into Icedove (with safe Icedove settings), when it has already been written
This is exactly the hands on, step-by-step guide that is required for usability. It needs to be referenced in the email section of the wiki.
Now re: usability of providers, Rise-Up and invites to the service is never going to work, plus they are located in Trump-Land, home of the dictator-in-chief. No sale.
This is why ProtonMail apparently working on a plug-in or otherwise compatibility with Thunderbird is the answer.
We are working on a solution that will allow you to use ProtonMail with other email clients in the future.
4 months ago
We are working on this, but we do not have an exact date when it will be available.
The issue was first raised two years ago though (don't hold your breath).