Looking for an idea for a project to work on while studying programming

I'm currently finishing my degree in Software Engineering and I'm looking for a project idea to work on alongside my studies.

I'd like a fairly comprehensive project that incorporates many of the tools and programming languages in high demand in the professional world (such as Docker, for example), without taking months to complete.

I'd like the project to be done in Java, C, C++, or C#, if possible.

I have a Raspberry Pi available, and I'm open to buying some inexpensive hardware (camera, sensor, etc) if the project is interesting.

I'd like something interesting that has real practical value, at least for my own use. Not just "rebuilding a web browser" or something I'll never use.

If you have any ideas, I'm all ears — even if some of the criteria aren't met.

Many thanks to everyone who participates!