I did this years ago. I had read a bunch of scare stories about Google cutting people off from their Gmail accounts and having no path to appeal.
I setup a domain name that is just my full name .com and used a mail service like proton or titan mail. I setup a few accounts (shopping@, work@, games@, myname@, me@) and gave them aliases, for example Shopping has paypal@ and Amazon@.
It is extremely unlikely anyone will want my domain name, so if my mail provider closes down or kicks me out I can just find another and repoint my DNS records to the new one.
I recently had issues with my DNS registrar primary servers going down, and titan mail was costing more than I liked when the renewal came up, so I've now moved to porkbun and mxroute and I'm very happy.
The 2 principles I stick to are.
Number 2 is hard to do sometimes, but worth doing whenever possible.