I think most people just don't realize how easy this is and you can even keep using gmail.

Most domain registrars have free email forwarding so you can forward *@domain.com to your gmail. This by itself is already good enough for signing up for things or resetting passwords.

If you also need to send from that domain in gmail there's just a few more steps: https://support.google.com/domains/answer/9437157?hl=en

Unfortunately it is no longer free to use a custom address in gmail; it used to be that just owning a domain would do the trick.