BlueKey

Kbin is developed by mostly one person, so yes, it progresses quite slowly.
But there is also Mbin with many improvements and much more active development.

I’m fully with you, that an API is still missing and would love to see it implemented in the future.

May I suggest Kbin (or Mbin).
It is compatible to Lemmys posts and voting and has also Microblogging.

The hidden services bother with a robots.txt file as much as the EU crawlers.
They can just start at an Onion link collection and start crawling.

Maybe an Android Emulator can at least help with the tiny screen problem.
+ More isolation without the need of an extra phone.

Proton

I think the Fediverse logo or something like this would not hurt.