I've had a google account for over 15 years, all of my email is handled via a (paid) google account and migrating it to something else is the kind of nightmare that I've been procrastinating over for a few years
I was in the same boat. I was paying Google over $30/month just for e-mail. I didn't move for years because I feared it would be a hassle.
In the end, I was able to move everything over to Fastmail in half an afternoon. It really was worth it.
Wow I just had a look at Fastmail and there's a quote on there directly targetting all of us that feel like this - "there's even a gmail transfer tool" :D
I did the same thing a few weeks ago and it worked well, Fastmail's documentation was also really good.
I'd recommend setting up your own domain for email with Fastmail too since it makes it easy to move later. Fastmail also lets you create aliases for individual accounts, I've used that to group together less trustworthy services.
The biggest time sync was moving all existing accounts from Gmail over to Fastmail. Luckily I use a password manager so they were at least all in one place, but it still took about a day of tedious effort.
What's worse is a lot of sites are just broken. They don't let you change your email or account name, they make you contact support to do it, etc. If you're in California you can at least file a CCPA request to force them to delete your account.
I was in the same boat. I was paying Google over $30/month just for e-mail. I didn't move for years because I feared it would be a hassle.
In the end, I was able to move everything over to Fastmail in half an afternoon. It really was worth it.