Huh, why did I not see that variable in the grep results... ah, that line didn't match because I negative matched 0-9 but not 'nothing' (end of line in the config file).
If it's just a configuration variable though, why bother migrating away instead of configuring it? Or even opening a ticket upstream that the 200 APs limit is causing issues if you would want to go that far. Ditching the software altogether seems radical
Unfortunately, NixOS makes it impossible to configure while NetworkManager is installed. This is because bss_max_count is a runtime var, so you have to use wpa_cli instead of a config, which requires a socket in a dir that NixOS conventionally keeps empty. I decided it wasn't worth the effort to fix.
If it's just a configuration variable though, why bother migrating away instead of configuring it? Or even opening a ticket upstream that the 200 APs limit is causing issues if you would want to go that far. Ditching the software altogether seems radical