You could track container ships, in fact they're probably so easy to detect you could run a small computer vision model on the satellite and only transmit those photos.

Obviously the most interesting container ships are the ones that you can see from space but don't show up on marine trackers. Although I don't know how you turn that information into money.

Actually someone must already be doing this, Airbus sponsored a Kaggle competition for detecting ships in satellite imagery https://www.kaggle.com/c/airbus-ship-detection and maybe that's how they caught that Iranian oil tanker last month.