Does it support Android tablets or iPhones?
Neither is supported.
Is it possible to switch applications using stylus pen?
Not available for application switching.
If you encounter the problem that stylus pen cannot work, how should you check it?
Make sure the stylus pen has power before trying to set it up again:
Settings--->Apple Pencil--->Turn off the Apple pencil.
Settings---> Notes--->Turn off "Only Draw with Apple Pencil”
NOTE: confirm whether your iPad is compatible before purchasing!
Please confirm the models is 2018-2021 iPad or iPad Pro.