MiX file explorer for android does this. It’s free. Not sure if it’s open source though, does anyone know?
It does use open source libraries.
Latest version is 6.64.3 beta.
https://forum.xda-developers.com/t/mixplorer-q-a-and-faq-user-manual.3308582/
“MiXplorer (Mix of Explorers) is a fast, smooth, beautiful, reliable and fully-featured file manager with a simple and intuitive user interface.” created by XDA member and Recognized Developer @HootanParsa
I wondered if there are other means, beside a mask or face cover, to not be seen. Like some sort of cream you put on, like you would sunscreen, that somehow tricks the camera recognition tools. ???