Sometimes it is useful to make useless things. It will build experience while being fun and making you more able to come up with "useful" things. Tried this with a friend of mine. Our plan was.

1. Take webcam at desk. 2. Build model that detects whether he himself is sitting at his desk. 3. If it is not him, you've detected an intruder, so spray the intruder with a squirt gun or something.

We only got as far as a model that distinguished between him and other people, even deploying it according to this guide. https://course.fast.ai/deployment_render.html

Also the material is just really interesting. If you want to know how a lot of products work, this is one of the most fun ways to learn.