You haven't been reading the right stuff. AppleShare client 1.0 works just fine on a stock 512K with 64K ROMs. You do not need any special software to log onto an AppleShare file server. However, it only goes one way: from the 512K to the server. I regularly logged onto my System 8.6 Mac from my 512K via an AppleTalk to Ethernet bridge. Check this out as well: http://www.vintagemacworld.com/apple_software.html
EasyShare suggests the 512K can be a peer-to-peer client/host. Actual practice may prove differently, but it would certainly not be alone in software that will do this on a 512K. I recall looking for this once upon a time to try on the 128K, before I learned how it actually implements AppleTalk and had no luck finding it. Let us know if you do!