I've got a homemade adaptor to put a phone onto my spotting scope.
Photo quality is variable. You need to zoom in or you get a circular back border (the inside of the scope)
Any vibration ruins your shot at distance. This even includes heavy walkers, using a timer is a must.
It's an absolute pain to focus.
You lose a lot of light.
Still fun to use.
Remember to check in every day to receive 10 free shutter pushes.