Yeah, Proton are working on delivering a privacy-focused replacement for the whole google suite. Mail, drive, calendar so far, plus VPN. OP could do a lot worse. :)
Posteo doesn't allow you to use your own domain, do they? I know OP didn't ask for that but it's a really, really good idea to put your email addresses on a domain that you own.
Still, it would be a definite step up from Google.