How about making an area in Argon space, that would be the museum of various Argon designs from all previous games.
I think the designs from X-BTF and X2 would need some facelift, but to reduce the work they would be stripped of all surface elements (e.g. turrets) as well as interior (lets say that Argons stripped them from all equipment and welded the interiors).
This would also serve as a prevention measure...because we all know we would try to steal them the moment we arrive tho the place

And we know some noble moders will turn them space worthy in no time

I don't think all Argon ships from all games would be possible, but most notable "Hero" ship.
E.g Various iterations of "Argo One" (since X-BTF).
Maybe some other significant ships, like Nova, Buster, X-Shuttle, some Khaak and Xenon war derelicts, etc.
This would be useful in multiple ways:
- easter egg
- atmosphere builder
- possible side mission (actual museum heist?)
- assets for moders