Just know that it won't make your games all of a sudden work well, you're still working with the same, old hardware.
But yeah, it's very lightweight, and it honestly probably doesn't matter what desktop you use, they should all be fine on modern-ish hardware. My laptop is all APU from 2018-ish, and it is still very usable, and my kids still love playing Minecraft on it.
A full install is something like 10-15GB. Any desktop should use <1GB RAM (usually like 300MB or so). You just don't get the bloat from MS and Apple, things just tend to need fewer resources.