The tricky thing with bit-banging neopixels is that the entire string has to be sent in sequence and the timing is quite tight. With the standard (modern) libraries you need the entire string ready to go in memory, which would've made things tricky with 90s RAM capacities.

Semi-related: non-real time systems like the Raspberry Pi usually need to make use of audio/PWM hardware for neopixels and thus can only control one string, but Jeremy Bentham wrote some fantastic code which uses the secondary memory interface to drive up to 16: https://iosoft.blog/2020/09/29/raspberry-pi-multi-channel-ws... .

Ah, yeah, I missed the 'addressable' bit, so they aren't a passive matrix. Fooled by the 32x8 module, last I saw they were all single row strips or strings.

Effectively they are a single row that serpentines across the display backing board. You have to send all of them in order to change the last one so they are 'addressable' but not directly addressable.