Super low end Arduino or a PIC board, or something equivalent in power.

But the Raspberry Pi has the advantage of a lot of computer power, and a full set of programming tools, which is nice.

I was thinking something like the RP2040 which is Cortex-M4 based. 8 bit Arduinos are nice and all but since you can get a 32 bit processor with hardware floating point for the same price points you don't have to "go that low."

Hadn't heard of the RP2040. It's quite impressive.

I see even the Arduino organization produces a board that uses it.

RP2040 is Cortex M0+. It doesn't have an FPU.

Ah, I sit corrected. I had made the erroneous assumption that the second core was and M4 not another M0+. Thanks!

Very true! But probably for different reasons. Interfacing to a micro-controller or a PIC is a bit more complicated than plugging a keyboard and monitor in.