Are you sure you want to do that? If you have all emails accessed from a single interface, that interface's IP address becomes associated with all of your email accounts. Doesn't go very well with your other threads about maximum privacy.
Tutanota is very nice. Protonmail has similar functionalities.
IIRC, Google Workspace accounts are subject︃ to an entirely different EULA and much stricter privacy procedures than free accounts. They aren't︄ scanning emails for marketing purposes if you're a business client.
It's still Google and lack︅ some of the fundamental encryption benefits of the likes of Tutanota and Proton, of course.︆