There are two aspects that make this easier than most people realize:
- You will theoretically retain your existing Gmail address forever, even if you close your Gmail account. This means you can reactivate it at any time.
- You can use your new email address as the sign-in ID for your existing Google account. This means you can continue to use Google Docs, YouTube, etc and stuff without being reliant on Gmail.
I wrote a short guide a while back here: https://www.justus.ws/tech/how-to-ditch-gmail/