A sub carrier would be beyond cool, but the fact that you could only have like 2 3 plane
squadrons MAX would make them not very worth while.

It would be cool to see some high level subs with scouts although they will need to
appease the surface ship players before they unleash another 2 tiers of sub on the servers.

sub carriers legit had the capabilities to launch 1-2 planes, and these were float planes with crap
maneveurability and as such had limited attack abilities.

All subs in NF have generally the same speed, and is capped at 40kn due to balancing.

Sub-carriers may be the IJN SS5 and SS6, but no one knows except the devs.