To be honest, at this stage, I'm a little worried about getting the
logic right. If someone managed to have a piece of code that works in
the installed system, I could look into doing whatever is needed to get
it to work inside d-i (dealing with Makefiles, build systems, linking
against libnl or whatever).
If someone had reference(s) of external adapters I could easily shop for
and get delivered to France, that would make the feedback loop shorter
(I'd be able to hack and build and test, instead of hacking and
building, then asking others to test).