your problem statement is very vague; keyboard is part of physical security and there is zero expectation of anything being private from keyboard to the messeng

your problem statement is very vague; keyboard is part of physical security and there is zero expectation of anything being private from keyboard to the messenger app input channel; one way to prune this clear channel and to achieve some level of privacy is to expose a virtual keyboard ui that controlled by the app, and user provides input via mouse clicks.