Jelly Star is really small, I doubt it's usual as an actual smartphone (but I understand the "under-smartphone" usage). For the people who want the just-big-enough-to-be-usable-one-handed (for average man hands let's say), the upcoming Jelly Max should fit better.

My current daily driver which fits that just-big-enough is Qin 3 Ultra. Its size is perfect, but it is no longer available (unless you want to use their original firmware, which ugh, no)

(Also anecdote, I once ordered a phone from Unihertz, I never received it. I couldn't cancel the payment because it was a kickstarter with few months delay...I won't buy directly from them again)

Of course none of the devices I mentioned (both Qin & Unihertz) are compliant with GPL and release their kernel source code...