Self-hosting is your best bet, in my opinion. Personally, I use Sendy[1], but
other options are Mailcoach[2], and Mailtrain[3], both options I am considering
switching to.
While they all offer the option of tracking opening, clicks, and whatnot, you
can disable these features easily.
The same can be said about hosted solutions, though, so maybe take a look at
Buttondown[4], if self-hosting is not an option for you.
[1] https://sendy.co/
[2] https://mailcoach.app/
[3] https://mailtrain.org/
[4] https://buttondown.email/