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.
Thanks so much for this, I'm looking into it now!
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.