I thought, I could use external HW keyboard for Jolla. The connection was made really good. Some magnets were holding keyboard in closed and opened state, but user could detach the keyboard completely.
But then, I have seen the layout, which was totaly strange to me. Yes, N900 had non-PC-KBD layout too, but I could reconfigure all keys in XKB. Second problem on Jolla (and probably most external keyboards) was, that there was only EN layout (I mean mapping, not labels on keys) and you could not change it. The same is on my Blackberry keyone - there is qwertz layout and I even cannot tell in Android, that I want czech qwerty keyboard. There is only qwertz czech keyboard. The Android Hacker’s keyboard is great onscreen keyboard for this. You have every key and you can change many features. But it is onscreen.
This is same as for other smart phone companies - to focus to main audience, which is BFU. In Librem case these are extended BFU, which want some more security and privacy. But the BFU thinks “I want buy the cheapest one”. So you have to make nearly the same HW as others to make it cheap.
As I have written, I understand that to make something new special needs many courage and much money (because of small production). And it will be expensive for end user, because of expensive small production, because major users don’t need/want these special features.