Maix Bit hardware
Only SD card below <32GB work well. This is due to a bug in micropython FS which can't handle exFAT When inserting an SD card, the boot.py from the SD is the one that's launched SD card file operations are rougly 1000x faster than flash so loading a 2MB model to SRAM is instant
The lens on this is very narrow and very dark, probably f3 stops and 80 degrees FOV so it's hard to frame objects and forget about doing NN navigation, also, because it's so dark you get a lot of noise in the image unless the room is blasted by neon light or you're in full sun. So to remedy that I swapped with this camera's lens which is also a 1/27" F1.2 @ 110 degrees FOV and look at the difference!
Before
After
Not only do you see more but it's clearer and less noisy.
You don't need to buy the whole camera though, these are 1/2.7" barrels, chose your F-stop and FOV:
https://www.banggood.com/search/1-2.7.html
https://www.amazon.com/s?k=m12+lens&s=price-asc-rank&qid=1558808867&ref=sr_st_price-asc-rank