FWIW I did run on old hardware with ratpoison and had a blazing fast experience, much more responsive than “top” hardware back then. So… yes IMHO it’s about the wm/de usually, the rest follows. Obviously you can’t run super demanding software, e.g. video editing, 3D modeling, etc but that’s usually rather obvious.
Yeah I don’t think you’re addressing what I wrote, you’re mixing up my suggestion (to clarify the important part is “or”) with DistroBox then more general comments. Might be that I wrote it unclearly but anyway it wasn’t what I was saying.