Protonmail and Brave do indeed seem like a good fit. Two somewhat sketchy, very commercial outfits that market themselves as more private than the competition and that will gladly break existing standards and practices to so.

They also seem to attract surprisingly similar groups of users, including a larger-than-chance overlap. Protonmail, in particular, seems to have become a sort of running joke as the e-mail provider of choice to send threatening mails in all-caps.