I use the mailbox offering of Posteo (https://posteo.de) and am very happy with it. They're a small business located in Germany that does not do any bullshit (no ads, no tracking, etc.), and ticks a lot of the checkboxes for ethical business (as much encryption as possible, careful examination of court orders instead of automated law enforcement access, exclusive usage of renewable energy, etc.). I usually go in via IMAP, but their webmail looks pretty okay as far as I remember. The basic offering is 1 € per month for a mailbox, a CalDAV calendar and a CardDAV addressbook; but I think you can sign up for a free trial if you just want to have a look.
(Not affiliated with Posteo, just a happy customer.)
According to their own accounts, they have not taken any venture capital or loans. And they say they're donating to NGOs on a regular basis. I could also imagine that users' deposits are invested. (They use a pre-paid model, and e.g. I always send 25 or 50 euros at a time when recharging my Posteo account. An average of maybe 5 euros times 50,000 users is a quarter million in free cash.)
(Not affiliated with Posteo, just a happy customer.)