Really need more info from you to be useful. What's the camera? What's the larger bin file that app.img came from? How did you extract app.img from that bin file with binwalk?
That said, I took a brief look. app.img is ARM little endian, probably v7, and you can load it into Ghidra. I'm not sure what the base address is. From googling an identifying string ...
my findings on openwrt forum
also a link to the update script which can be helpful to see how to decode the firmware from github: https://pastebin.com/SXASpfnX