@jaseg That's what I wanted to try. In my case the interfaces with each of the modules are very well defined, so I wouldn't have issues with the connector pinouts not being synchronized.
But still, testing the modules requires to make one core module, with all the connectors coming out from it, and then start making module after module... in separate kicad projects? uhhh
Also I have to deal with a few (not-very-)high speed signals and I don't know how the connectors and flat cables would do