DeGoogle Yourself

I'm pretty far into the degoogling process, and I'm thinking about purchasing a domain and using it for email. I realized I don't want to be stuck with any one email service, so this is pretty much a necessity for me.

I wouldn't self host though, because I understand that's very hard to do.

For people who have already done this: are there any pitfalls or things I should take into consideration before I purchase a domain?

Also, does the tld matter? Are my emails more likely to be sent to spam with a custom domain vs an email provider's?