Hi,
It's not a rant, just curiosity. The only "mobile hotspot" device that is supported by OpenWRT seems to be MUDI from OpenWRT. There is a plethora of ZTE Uxx devices on the cheap out there (like U30, U50 etc). What is the reason OpenWRT is not supporting them? Is it some kind of closed-source SOC, inability to flash them without specialized equipment etc?
yes, those are closer to screen less cell phones, than routers.
technically, you could transfer the image over serial.
This topic is relevant: Work in Progress Kernel for ZTE zx297520v3
With that SoC, a lot of these devices should start to work. You can flash them without special equipment, but it depends on the model how easy it is. The flash memory seems rather cheap though and tends easily break down unfortunately.