Fastmail rocks. I decided years ago to be the customer not the product, so I don't mind paying for services I use.
An added benefit of Fastmail is somehow its calendar is able to sync between my Outlook work calendar and some shared Google calendars I have, while Google is completely unable to reliably sync a shared Outlook calendar for me.
Not parent but the more important thing in "de-googling" is to move your logins to your own domain. That way you are not tied to a single provider and can always switch if your current one starts degrading.
After over a decade of @gmail being my primary personal email it is pretty painstaking to move all of my logins over, and some services do not allow you to change your email at all so your mileage may vary.
Several months ago I moved my family's email hosting to Zoho. Its been pretty solid. The web client is really nice, its got pretty good mobile apps, it provides IMAP/Exchange Sync on their cheapest paid tier so you don't need their apps. Zoho has a 5 user free tier of just email, but you're then limited to their apps. I'm using the Mail Lite tier with the larger 10GB storage which is $1.25/mo/user billed annually.
They have some tools to migrate email. I was migrating from an IMAP source, the migration was pretty quick and painless.
I would recommend Protonmail because you can also have a plan that allows you to use your own domain. The interface is much better than Google IMHO and the spam filtering is up there as well.