How about https://github.com/NeoCat/ESP32-P3RGB64x32MatrixPanel?

Has anyone looked at that lib to see if there is anything interesting in it or extra hardware support that might be missing in SmartMatrix?

I asked here https://github.com/NeoCat/ESP32-P3RGB64x32MatrixPanel/issues/12 but haven’t heard back yet.

Haven’t seen it, thanks for the link!

Note that this library heavily use the timer interrupt to drive LED matrix to enable software based 5bit PWM for each line

Doesn’t look very advanced: no DMA, low color depth

That was my thought too, seems limited like you said. I have no idea why the author wrote this.
Then again for situations where you run out of DMA memory (either 128x128 that won’t fit at all like you warned me, or my current problem I’m looking into where my combined code also runs out of DMA memory for now
Can't get enough DMA memory on ESP32: assertion "matrixUpdateFrames[1] != NULL )
it may be better than nothing