Back in June 2020, I redrew the icons using @BlackYps template and some mild inspiration from the old Advanced Strategic Icons mod. I made versions essentially identical to the symbols in vanilla and optional layers in GIMP for things like a wrench or missile shape for engineers and whatnot. Since I have a 4k monitor and bad eyesight, I started with ExtraBigHugeLarge size (4x vanilla, I think?). When I stuffed them into the game, the UI scaling code magnified them so they would cover the build icons (the full color ones that show what you're queuing up to build) and since I can't code my way out of a paper bag, I just sort of gave up.
I'd be happy to contribute what I have so far, and even do the in between scaling if someone is willing to do the surrounding code so I can have big icons on the map, but not covering the build icons.