I'm still trying to get my head round why navies would even be a thing in the future? Or how airforces work with varying atmospheres... I think they'd be fun additions but, particularly with navies, how would that be justified, lore wise? They're a thing on earth because we've not developed air/space tech enough that it's outdated, but I don't really see why Shadow Empire would really bother with boats at all... I guess if the argument is that each planet is rediscovering technologies, there'll be a brief, earth-like period where air power isn't quite good enough to project itself across the planet, and maybe carriers might be necessary there for a short while, but after that?
There's a lot of latitude for story-development on that; "a short while" could be 500 years, for example, if the author puzzles it in that way. Air forces, and other analogs that remain aloft without atmosphere, might exist but not be capable (for centuries) to mount or supply a D-Day sized invasion, for example.
Or, the relative relevance of navies vs air forces vs ground forces might vary widely depending on planetary conditions and the happenstance of discovery in a particular game. This is the way I hope it ends up - one game, navies might be critical, and the next anti-grav barges are discovered early and ocean-going ships are never built. That could make for some great variability in play.