You don’t really need Justin Alvey’s project to be active maintained, though.
I personally quite like Justin’s implementation, but the Home Assistant community has adopted the hardware and adapted the concept, and you’d probably want to use ESP32 software instead, like demonstrated by Mark Watt here: HOW TO - Replace Google For an ESP32 (Onju Voice) (youtube.com).
I guess the hardware generation still is a problem, though.
The Google Nest Mini (2nd gen) has a wall mount screw slot on the back. If your device doesn’t have a wall mount screw slot, it’s a Google Home Mini (1st gen).
And what @voltie says is true, these things are in active use via Onju.
Slightly off-topic but suggest post in this new thread as well for discussiing the possibility of someone creating an updated “Onju Voice” circuit board using Home Assistant Voice PE open-source designs for a new drop-in PCB replacement for existing Google Nest Mini speaker and Google Home Mini speakers as think that concept could be of interest to same people looking to replace their Google minis: