I mounted a dashcam with front and rear camera; brand is VSYSTO, quality is decent but not good at night. I did put the main unit under the seat, so the sound is not great from there, but it will turn on and off with the bike. The cameras have a very strong glue but I put some safety zipties around in case the glue fail. Since my bike don't have much fairings to hide stuff (2022 SV 650) I had to pass them behind some very little passages around and I have to find a decent fix for the rear camera cable that is just hanging a bit out of the bike.

Something close to it already exists: https://delta.chat/en/