The app lets you check if your phone can act as a bluetooth mouse or keyboard with the help of Bluetooth HID Device Profile in android pie and above. Some manufacturers have blocked this on android pie so you can know for sure.

You can also share the details with us via email or github of your phone manufacturer and phone if you want to so that we can try to reach out to your manufacturer for enabling this feature or atleast publish the record of phones not enabled on the internet.

This app uses an open source library : https://github.com/jaredrummler/AndroidDeviceNames
which has a license [ https://github.com/jaredrummler/AndroidDeviceNames/blob/master/LICENSE.txt ] and copyright [ Copyright 2015 Jared Rummler ].