If you want to build a "mars rover" yourself you can even simulate that at home :-)

Use LoRa in the slowest and most reliable mode as radio link. Write software to plan your tours, firmware updates over super limited bandwidth (delta updates are a must), transfer telemetry (buy a few sensors from ali) or even pictures. Autonomous driving? Yes why not.

Bonus 1: build a small PCB with a solar panel and charging circuit. That doubles the horror.

Bonus 2: Place it into your families garden that is at least 1km away.

Lots of very hard challenges to tackle for even super experienced programmers.

It's even a nice group project for an university lab. If you have to connect a real debugger to get your bot running again your team lost.

You can do even more than that if you want to see it moving! And without designing it completely by yourself.

https://github.com/nasa-jpl/open-source-rover