Through wrt. docks there is some non standard compilant parts about switching to the "dock" alternate mode, maybe I misremeber and that can't damage your switch.

Anyway if you by anything but super cheap potentially broken chargers in 2020 I would be very surprised if it damages yours Switch. Especially laptop chargers tend to work very well with it. Actually I observed (but maybe wrongly) that somehow my Lenovo think pad laptop charger does a better job when charging and at the same time playing in handheld mode .