On a side note, looks like others have made some good headway on a Perspective-native solution for on-screen-keyboard:
Forum: https://forum.inductiveautomation.com/t/perspective-text-field-numeric-keypad/71229/26?u=chris_bingham
(Edit: Updated Link) Blog: https://aott33.github.io/2024/07/25/perspective-keypad.html
Exchange: https://inductiveautomation.com/exchange/2380/installation
I still like the idea of OS keyboard (mobile users vs desktop vs touchscreen, etc.). However, that Exchange keyboard is looking promising.