None basically. There’s a Sony phone has LineageOS (including +microg variant) support, but it’s not ideal either.

If you are open to building something yourself this might be an alternative (disclaimer: I just know of this project but no idea how well it works): https://www.findmycat.io/

Use Clevis either with TPM or Tang (remote server) https://github.com/latchset/clevis

Obviously that was a controversial decision, but Red Hat probably contributes to Open Source more than any other company. To call Red Hat “OSS Hostile” is probably a little too much.

The most important thing, if you intend to do outgoing email, is to get a reputable hosting service, where you’d have few/none bad neighbours. Unfortunately that often doesn’t come together with cheap, as cheap solutions often attract a certain clientele. I’ve also had more luck with slightly smaller (but still reputable) providers, i.e stay away from OVH / Hetzner and the like. If you want something cheap, it’d probably not be a good experience to self-host.

With my self hosted solution I have no concerns about deliverability, and only very few occasions had blacklisting issues (due to neighbours in the /16 range).