I have been thinking along those lines myself.

I have been playing around with a per scanline generated display on a rp2350 outputting to a tiny LCD. I think there's potential for some pretty fancy stuff on HDMI. A 2350 with PSRAM, HDMI connector plus a MicroSD for bulk filesytem, and USB for input could be quite a fun micro PC.

I would be tempted to make somthing that had a second RP2350 with its own PSRAM sitting unutilized just as a temptation to users to figure out how to get more out of the gadget and learn about different multiprocessing architectures.

One of these https://www.waveshare.com/core2350b.htm

With one of these https://www.waveshare.com/rp2350-matrix.htm

Mounted on top, and an HDMI connector squeezed in somewhere,

I am a bit reminded of what GeoWorks Ensemble managed on a 640k 8086. Theoretically you could make a tiny system like this do even more.