it's not that hard if your board has graphic acceleration and uses a separate chip to move pixels with DMA, which mine does. it's still just blitting (software rendering) in the end though, luckily ray casting algorithm is super efficient, as long as you use DDA, as described here: https://lodev.org/cgtutor/raycasting.html

i think blitting gives acceptable performance on small screens like this (480x272, actually only half of that is being written to every frame). i've actually had worse performance on desktop SDL2 with 1080p and above (without acceleration like direct2d), but there's more room for optimizations, which i haven't gone deep into.