Services cost money to run. Either you pay for the product or you are the product.
Make your choice, name your poison. No skin off my nose in any case :)
It's not Tuta but I adore Fastmail.
No BS. No gimmicks. Just privacy aware, protocol conformant E-mail at a reasonable price.
Apple does not care and will never care about open source other than the bits it has to care about because they're a part of Darwin, their core.
They're a company offering a particular "experience" and open source products do not fit into that model well at all. I use apple phones because I'm partially blind and for a very long time the accessibility story on Android was a screaming nightmare (I'm told it's got better) but I have no illusions that they're anything other than a profit seeking MegaCorp with all that implies.
Self hosting email is a non trivial effort. I've done it before and am in zero rush to do it again.
And before you tell me "Oh hey I've had no problems at all with delivery getting blocked by GOOG or MSFT" good on you but that has NOT been a lot of people's experience trying to self host their E-mail, including mine.