Another tool is paperless ngx. Although it is a bit more than just a scanner Programm.

Reolink has always been a good choice. Very good hardware for the price and they support onvif on most devices, which you can then use however you like.

The fact that the ccc uses matrix as their official chat “app” doesn’t imply that it is inherently insecure I would say.

Try this one

https://play.google.com/store/apps/details?id=com.spocky.projengmenu&hl=de&gl=US

Been using it for a year now, really happy with it.

Yup, that’s it, at least from my understanding.