HDMI-2-CSI2 adapter uses the same CSI port as regular CSI camera. So from system point of view it looks like regular camera with a little bit different configure steps.
For reference: https://geekworm.com/products/x1301
Thanks for the explanation, that makes sense to me. In contrast to WebRTSP Camera, the snap name does not make it evident to the user that it will have access the camera. However, I expect it to have a limited impact considering the scenarios where this snap is meant to be used.
+1 from me for granting WebRTSP HDMI ReStreamer auto-connection to camera and media-control interfaces.