I was really surprised by how hard it was to find collections of old knobs and dials and whatnot. Some of these are taken from the Flickr group control panels but lots in the group don't focus on legends and dials in a way that's useful for inspiration for pedals. These are mostly vintage military tech and early electronics and computing.
A great source related to the early computer terminals and keyboards is r/mechanicalkeyboard's list of keyboard fonts. They're mostly just riffs on Helvetica and Futura, but interesting nonetheless.