The Sonim XP3 Plus uses Android 11 Go, which unfortunately suffers form a bug that prevents virtual mice from being able to click (some Google dev accidentally set non-touch devices to get filtered out when finding where a virtual mouse click event was received). It was fixed in Android 12 Go and was supposed to be backported to Android 11 Go quite a while ago. The dev behind matvt said he cannot find a workaround.
Unfortunately, I think it's pretty unlikely this phone will ever be updated far enough along to see that patch if it hasn't already. Sad reality is dumbphones (or any cheap Android phones, really) rarely get any updates beyond what comes with them.
If the virtual mouse function is critical for you, I'd recommend returning the phone and getting either a regular Sonim XP3, Schok Classic (NOT the Schok Flip, which also runs Android 11 Go) or something with a touch screen, like the CAT S22.
