I run Pico-8 from console, without using X on any of my Raspberry Pis.

Sometimes I have a second framebuffer device at /dev/fb1 that I want Pico-8 to run on.

Right now it looks like there is no way to get Pico-8 to run on any device other than /dev/fb0.

This would be useful for running Pico-8 on a connected LCD, 2nd monitor, or USB DisplayLink device.

I would also be interested in this!!

I think they changed from SDL (which could be piped to the framebuffer) to SDL2 which can not

you can work round it by using fbcp to just copy the normal screen output to the framebuffer, and it works well enough (also give you the added bonus of HDMI mirroring for big screen play)
https://hackaday.io/project/20152-gameboy-zero-but-smaller/log/54847-piezo-and-pico-8

Wow is this really the app's responsibility? I would have thought the graphics lib should be able to be configured to provide a surface to the apps without them having to worry about it (much like X has the DISPLAY environment variable). Not saying you're wrong of course, just surprised this is something that every SDL2 app needs to expose as an explicit configuration option.

I came here to come with an additional use case for controling the Frame Buffer used. Raspberry Pi 4 (and Pi400 and CM4) have two HDMI port, so it would be great to dedicate one to Pico8 (that is also the one I would like to mirror on a small LCD with fbcp).
But maybe there is another way... I'll try reporting here if I find.