Zero. All this "HD games are expensive" is a moronic and untrue narrative that handheld fanboys like to tell themselves to justify their bottom shelf hardware.
More hyperbolic than untrue. They are correct that AAA games, or in this case what would've been considered AAA on a handheld, will take longer and cost more to make on Switch due to its increased power and console nature. It's a reason why Fire Emblem had to be delayed twice, expectations are higher. That said, HD-development is generally speaking, a non-issue for the most part. As I said, Development tools are so versatile these days that Even PS2 styled action games can be done by a couple guys in Unity over the course of a couple years. Indie developers are showing that "HD games are hard" is an grossly outdated mindset.