Worked as a computer repair tech forever ago. We ended up with tons of spare parts and abandoned computers. I took a few home and looked for things I could use them for. Quickly found Linux and gave it a shot. It was perfect, I didn’t need to spend $100+ for a copy, there were tons of options, and I could do anything with it. Spent the next 20 years using it on every computer except my main desktop because of games. At one point I was 100% Linux and all I played was WoW using WINE. Now I’m back to 100% Linux thanks to steam and proton making a healthy chunk of my library playable.
Any time someone comes to me with an old computer my recommendation is to throw Linux on it and get a few more years of usefulness out of it.