I already use Tuta as my email provider. I already have a domain I can use with it (bought privately). What privacy implemcations does it come with.
The main reason is because I would like to be able to keep the same email address for longer and not have to change when/if I change providers.
I do this. Its great because of catchall emails and the ability to make one address per merchant. Then if a company leaks your email or gets hacked, you can simply change the email from hacked-company@domain.tld to hacked-company2@domain.tld and block the old address.
It also is good for ownership as you said. If Tuta gets purchased by Google (for example), then you can simply pivot to any of the many other email providers and not rely on a company being not evil.