I think it's "Piece to Camera", which took quite some digging to find!

Yep. PTC is Piece to Camera and VO is Voice Over.

Push to chat, no?

The context is video creation: "It's more editing work but I like to split out the screen recording, VO, and PTC."

Piece to camera is talking directly to the camera, unlike a voice over while showing something else. Makes sense to me, but I'm guessing a bit.

How would "push to chat" fit in? I don't recognise it.

Was thinking in context of gated voices, background noise etc. Think it’s actually push to talk, so I’m not right on reflection.