It’s not exactly what you’re wanting, but there is Remote Video Camera on F-Droid.

If I were doing it, I would look for an app that just implements the same basic functionality as a network-connected camera. Then video storage, alerting, motion detection, etc. would all be handled by something like zoneminder.

From the README at the current published commit:

> The current focus is on implementing next-word suggestions, which has become complicated/hit a snag and is taking more time than originally planned. Updates will come when this issue is resolved. Thank you for being patient.

Prior to this, releases occurred quite regularly.

Matrix doesn’t require you to set up a server.