I'm interested in seeing where this goes. While I will admit that Bretonia likely wouldn't give out their tech to other folk regularly, Liberty has been an ally of Bretonia's for the longest time, even before Disco's canon took effect. Both houses primarily speak the same language, have roughly the same culture (one is obviously more capitalist while the other is considerably more authoritarian), and have historically, even before the exodus, have good allies of each other for centuries. I'd find it believable that at least one Bretonian battleship would make it into the Liberty Navy.
Plently of player ships already stretch the canon anyway, so I don't see why this can't either.
Just don't defect it or something.