[KwanEsq]

Well that depends, the camera app is generally accessible on locked phones, so the question is, can the camera app make use of USB-connected cameras, and if so is there any restriction on accessing such cameras in locked mode (like there is a restriction on accessing past photos).

[hkwerf]

I'm not sure, most vendor camera apps were pretty much tied to the particular camera on the phone, on the phones I've had. For UVC, I usually needed to use another camera app.

You could try to initiate a video call with the locked device, though.