Microsoft managed to build office online, which saves to DOCX etc. - the online version may have reduced functionality, but you can edit the same document with the full office at work and the browser version at home and it won't mess things up. So building a new office on top of the MS formats seems possible. You could probably even use AI for the things the other (open/libre/...)Office developers can't or don't want to do.

Ghidra-MCP is allegedly really good for reverse engineering. Haven't tried it myself.