I think it'll work just fine with USB/Bluetooth mouse out of the box, you just have to turn the cursor back on in the video settings, if it was disabled. I mean, Android build of the game is literally a direct port of game's PC version which supports mouse, so..
That's a rather weird way to control it lol. We support either mouse, or touch, no in-between shit like this. If you really want to be a masochist, then I suggest you try running Windows version of FloppyScryption in Winlator, IIRC the game functions fine in there, and Winlator has mouse working this way. Though at this point you might as well just run the original game in there XD