Fedora and Arch both work pretty well on 4gb. Plasma and Gnome were surprisingly decent, and xfce was great but a little uglier. Blender, FreeCad, Minecraft (with performance mods), Celeste, for example all worked perfectly fine, with maybe a few browser tabs in the background as well. You couldn't do anything too heavy, but it was pretty usable (I was using it as a travel laptop mostly). I'd say 2gb is where it becomes too little to live with.