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.
I would instantly throw away my IPhone (despite being happy with macOS/iOS) for a Blackberry like phone with LineageOS.
https://pineguild.com/pinephone-keyboard-first-impression-is...
https://ebay.com/b/BlackBerry-OS-Unlocked-Cell-Phones-Smartp...
Yup. I could type accurately and drive at the same time (don't do that today, kids) simply because I didn't have to take my eyes off the road at all. Those little raised bumps on F and J keys helped.
https://www.amazon.com/fosa-Wireless-Bluetooth-Keyboard-Port...
Really loved my Q10 with bb10os and my Keyone running Android! Sadly security updates stopped so had to get a slab, and run Blackberry Inbox on it (unified inbox of all your messaging apps, it is quite nice).
BlackBerry licensed Onward Mobility to make another keyboard phone, although they promised one this year, they are so silent I would be surprised if they are able to.
Bb10 was really a supernice OS, a lot of android and iOS stuff is inspired by it. blackberry still has some amazing patents and software, so it isn't a goner, but no phones directly from them anymore, only licensees (India, Indonesia, and hopefully worldwide via Onward Mobility)
I never knew the glorydays of bb07, but sure know if they stayed succesfull then (I.e. made less catastrophic mistakes and made strategic choices away from business products when they had a significant mobile phone marketshare ) how cool it might have been now with them still in the mobile phone field.