So from some googling it looks like the biggest nuclear subs top out at about 30MWe of output, which is roughly the same as EDFs West Benhar wind farm (https://www.edf-re.uk/what-we-do/onshore-wind/) which has 7 onshore wind turbines and can power about 18,000 homes.
Subs reactors will also be designed around the needs to power the sub with will presumably have much different load requirements to commercial nuclear power station.
I'm also willing to bet it isn't exactly economically viable running it long term.
Slightly related but there was a time they used a engine as an emergency generator for a town https://youtu.be/FWYbD2ga8DM
I don't run my car indoors because generally it doesn't fit through the door.