Sounds like a screen overwriting shader, not sure which one it'd be using though (and the audio would just be a toggle that you'd have turn on when you turn on the shader effect)
@Lilpuppy I believe I can rip for you, I'm kind of surprised nobody else has figured out a way to do it. Give me your Discord and I'll contact you at some point, for so many avatars it wouldn't be very cheap they take a lot of work just so you know.
You might just have to re-rig and weightpaint it by hand, setting up the rig would be pretty quick/easy since its just creating bones and positioning them but the weightpainting part would take quite a bit of time. Id also guess based off how the bones are around the face you'd need to create your own visemes and eye look
Blender is the best way. Bone scaling usually doesn't come out properly or in a way that looks normal/accurate, So sculpting is absolutely the way to go.
click on the fbx of the model, you will see milltina inport <--- that will popup in the inspector settings and enable Leagacy blend shape mormals same place you make the model; humanoid
Also to clarify, I have only been using 2019.4.31f unity and not 2022. It seems it is also uploading my image at a 800 x 600 resolution too along with its terrible compression which makes no sense to me and also turns it out far worse. I've been dealing with this problem for months now and seriously have no idea what the problem is.
I rip from cache very often and have had no issues with it. I will point out that I manually repair avatars instead of hotswapping, which could decrease ban chances. You should be fine if the avatar isn't before 2019 unity