In Android world scrcpy utility exists to just run and mirror device screen in a window.

While Casio app may be despicable, in Android world have a look at https://gadgetbridge.org/.

Gadgetbridge is open source provides a lot of "drivers" for different BT devices from Casio, Sony, Pebble, Garmin to Xiaomi and allows to live without monstrous in size and tracking proprietary apps.