Shouldn't that be the OS's task? My kernel knowledge is rusty but I remember reading about concepts such as DLL/SO sharing, memory page sharing, etc.

This works for libraries/frameworks installed in a common place, like /usr/lib or /Library/Frameworks.

But, all those apps ship their own copy of Electron, so there is no simple way for OS to share pages.

Well, then this seems more of a packaging problem than an actual tech problem.

In an ideal world that would be the next step if the app reaches a large audience. I'm not sure that from the upstream developer's point of view the investment of limited resources into per-OS packaging is a good idea at this stage...