I have a hackable switch that’s always sat in the dock, and only played 4-5 games on it since purchase,
It’s bately ever been used and the OS hasn’t been updated in a year....
If I’m interested in selling it not updating the OS is seen as a value booster for a prospective buyer who wants to hack it right?
You don't need to hack the OS. The USB firmware is vulnerable no matter the OS. That's one of the reasons for the two new models.
The value may go up, assuming they don't find a new vulnerability, but I doubt it.