Physical mouse

Android supports physical mouse very long time, however fully supported is only from Android 8+. Older systems are limited.
Android 7 and older
Older systems will see double cursor - game cursor and android cursor. Biggest limitation is that android stops sending mouse coordinates when cursor reaches screen borders. This can be fixed switching from "Relative mouse" to "Absolute mouse". However not every game supports absolute mouse. Some games can support absolute mouse after manual mouse resolution setup in advanced settings. By absolute mouse is recommended to make a screen a bit smaller (in "Adjust screen" menu) and center it (use long touch gesture to unlock screen). Else may happen, that mouse will not scroll in some direction.
Android 8+
Android 8 and newer systems fully support physical mouse. By default is double cursor displayed, but can be hidden by pressing mouse wheel. Wheel up displays menu and wheel down toggles android cursor visibility (The same can be done with "Special widget", see action "Capture pointer"). In this case are coordinates reported correctly.
Summary
•devices with android 6 and older can’t hide double cursor and must use absolute or relative mode
•devices with android 7 can hide double cursor, but must use absolute or relative mouse mode
•devices with android 8+ can enjoy fully functional physical mouse without double cursor and without any limitations
•devices with android 7+ can toggle android cursor visibility with mouse wheel DOWN action (or with Special widget)