First camera started working on a Hardwaee 4 equipped Model 3 (2022). Yes, we did the retrofit!
It’s not as bad as it seemed, the computer replacement needed, some light ECU hacking. No need to replace camera cables as well, you can get away with adapters.
It’s driving, but still a bit of stuff left to get all the features 😁
Honestly Tesla could have done it ages ago and offer a paid upgrade, if they end up doing it it doesn’t need so much new parts, but you need to replace all the cameras. It can be done on intel cars together with a Ryzen retrofit.