I really am surprised that with of all models of Android phones in the world, no one is making one with a keyboard. Even if it was a niche product, you'd think there would be an audience...
Before that a blackberry Passport which ran BBOS. Loved it too, at the time.
These devices do exist, and the niche is strong enough to support a small market segment.
The best thing Unihertz could do in my mind would be to dump a bunch of support and money at LineageOS and get their phones supported. Especially the one with the DMR walkie talkie; the lack of third-party support for those is crippling them.
https://www.indiegogo.com/projects/astro-slide-5g-transforme...
With all existing Android users, even if just 0.1% would like to have a keyboard you would still have a business ( https://www.businessofapps.com/data/android-statistics/ - assuming that only half of those 2.8 billion android users use a mobile phone and not a tablet or something else, that would still give you a market of 140M potential customers?)
Maybe it's about patents (keyboard tech)? And/or maybe Android users are really stingy (I would pay +50$ for an integrated keyboard, maybe most would not)?
Don't know, big mistery.