I have often wondered if there would be any interest in an ultra-low-cost computer based on the ESP32. I would speculate that RetroBSD could be ported, or perhaps Minix 2. Considering that the ESP32 delivers WiFi, Bluetooth, various peripheral interfaces, and several MB of flash and RAM (plus the option of an external SD card for bulk storage), it would seem that it should be possible to build a multi-tasking UNIX-like OS that could run on it.
I think that this post demonstrates that is clearly possible.
One could imagine a “laptop” type form factor delivered for on the order of magnitude of pricing as the Raspberry Pi. For such a low-power system, it could probably run on AA batteries. Obviously such a system isn’t going to have the multimedia capabilities of the Pi, but I think it could be quite sufficient to be a useful programming environment for students, kids, or hackers. It is easy to forget just how much you can do with 240MHz and 520k of RAM (or more, if off-chip memory is used).