Yes. I purchased an L-shaped adapter to mount the binoculars on the tripod. I also bought a mount to attach the phone with the binoculars. Attaching images for reference.
Hello. Yes, you can use this mount with any camera phone including iPhone 8 Plus. It doesn’t matter how many cameras the phone has. You would just have to adjust the phone so as to align the primary camera of the phone with the eyepiece lens. I have OnePlus 6T which has two cameras.