instead of the 128x32, can other sizes of displays from this same Itron company work?

Instead of being snarky, I'll try to answer your question.

Probably not. The empeg's display and native and only format is 128x32. While you could conceivably use a differently sized display, you'd have to map 128x32 pixels to it, so that seems a little useless.

In addition, Hugo (altman) is one of the original developers of the empeg and he's modifying the player software to drive it. It's probably unlikely that it will get released as he has developed it, and we, the empeg-using public, do not have the requisite access to the player software to reproduce it. At the very least, I wouldn't hold my breath. So any thought of getting it to work quickly just by using his software is probably not realistic.

There are some other folks that are attempting similar things inspired by Hugo's repeater. You might want to take a look around in the programming and technical forums for information. (I forget who they are or what the thread titles would be; sorry.) They haven't publicly gotten too far, though.