Anyone who opposes mass surveillance should.

I personally use Obsidian, but I know that other have suggested logseq. Might be useful to have in your table. Also, Obsidian does have an Android app.

You could get a raspberry pi and a camera module. MotionEye can be installed as the OS. It requires a network connection to your LAN to set it up, but it can be disconnected afterwards. I believe it can be configured to store all files locally.

Edit: Fixed link