The previous version of Plethora for Minecraft 1.12.2 allowed right clicking an unbound keyboard to open the keyboard GUI, which could be used together with the overlay glasses to get mouse input using the glasses_click, glasses_up, glasses_scroll, and glasses_drag events. The rework of the keyboard code removed this feature, resulting in broken feature parity.

Here is a video comparing the behaviour in 1.12.2 plethora and 1.19.3 plethora:
https://cdn.discordapp.com/attachments/198130613759246337/1066373211538853978/Jre-8.0.332.9-hotspot_2023.01.21_-_18.04.38.12.mp4 (discord cdn link because of 10 mb file size limit on github)

You can also mimic this behavior with introspection modules by getting player look for cursor control, and use something like sneaking for click events.