For my long range Aniioki ebike I added gold bar end caps so needed an option for a safety mirror. With a crowded handlebar setup, I decided to try the Parkvision Rearview Camera from Amazon.
I ended up attaching it to the battery handlebar at the top of the frame. It works for now though i may bring it up to the left handlebar and try to move my phone mount to the other side.
I have been riding with it for about 30 miles now and it works just a s good as any mirror does in my opinion. The main drawback is likely that you have to charge it every other ride. Battery should last 5+ hours or so. It has a 1080P HD camera, with an angle of 110 degrees. It works well at night also. Screen size is 4.3 inches.