You can google "electron size" and you get different classical estimations and hopefully a statement that there is no measuarable size and that it is considered

You can google "electron size" and you get different classical estimations and hopefully a statement that there is no measuarable size and that it is considered a point particle. But that doesn't mean it can't have interference. Interference occurs because of the wave function. The wave function for the electron and the electron itself are two different things. They did a electon double split experiment where they fired electons one at a time. The electrons each made a single point (or small mark) on the measuring screen, but over time, the interference pattern formed. (To be honest I heard this back when I was learning physiscs, which was along time ago. It could have actually been a thought experiment or it could have been something besides an electron. Anyway I believe it is true.)