I'm building a nextlcloud server. Just got the document server itself working a couple hours ago. My email back end will apparently be Mail-in-a-Box, although I've not gotten that far yet. That's about as private and in control as you can get. Run your own mail server.
Thoughts? Hmm. Well this is somewhat tangential, but you mentioned your email forwarding needs. I've used this ImprovMX forwarding service for years. Free tier really is free. https://improvmx.com/