Earlier quoted context omitted.
Switching email isn't nearly as friction-free as switching your browser. Not only do you have to change your email in every service you've registered for, you also need to convince your friends and other contacts to use the new email.
The most important change you can make for your email is to own your own domain. Once you own your own domain, changing providers is much easier since it is transparent to the people that email you. Even if you decide to keep Gmail, you should switch your email to your own domain.
Do you pay for Google Domains, or just have some other thing forwarding to gmail, and gmail configured to send with that as a 'from' address, which I think is possible? What's your advice?