i tried adding display_hdmi_rotate / display_rotate / lcd_rotate / display_lcd_rotate =1 in /boot/firmware/config.txt but that only works if i disable kms which causes pico-8 to fail to boot.

i'm running whatever version of raspbian you can get pico-8 rotated on. raspbian full with cmdline boot, raspbian lite, 32 or 64 bit.

i added video=HDMI-A-1:800xx480M@60,rotate=90 to cmdline.txt and that only rotated the cmdline, not pico-8.

You can rotate the screen in config.txt using the transform_screen option. I don't recall ever seeing a display_hdmi_rotate config option in config.txt but I also haven't looked for one. If you need to rotate the whole window, I'd think that was an OS/window manager config option and not a PICO-8 one.

I meant /boot/firmware/config.txt , but this helped. Thank you for freeing me from this never ending issue.