I dont know if they still sell them but all the old polar watches used to do this. Downside is you need a chest strap and you can’t download the data from the watch.

You can get cheap second hand ones online. I would have recommended the rcx5 except the straps break and it’s impossible to buy new ones…

Is this your first programming language? If so I strongly recommend Harvard’s CS50 course. It’s mostly in C but it’s very well taught and you learn enough fundamentals that you can quickly transition to another language.

I dont think that’s an unpopular opinion