Countermail.com if you manage to get an invite

Self hosting email is pretty much impossible nowadays. You have to use your hosting service servers at a minimum. But a dedicated email service will probably have better spam handling (although that’s possibly not as bad as it once was).

Proton Mail as others have suggested is the easy and privacy friendly solution, and probably set an auto forwarding rule from your gmail account to your new Proton Mail.

Otherwise I haven’t self hosted my own email but from my previous attempts it seemed like it’s quite involved

Not married to my email and I bought my own domain.
The only hard part is switching all accounts to the new domain (and finding out that some IT/dev departments decided that changing emails doesnt happen at all).

I pay a company a bit too much money so I don’t have to worry about self hosting.

I personally use mailbox.org for emails and anonaddy for aliases

I’m not saying that is the only good option, but you should look into proton mail.

Fastmail with a custom domain. It’s great, and has a nice migration tool for moving everything over from Gmail. Also integrates nicely with 1Password for personalized email addresses for each service I sign up for, which I can nuke as needed if needed.