I haven't, but I suspect it would work well on a Switch hacked up with homebrew firmware and would not work on a vanilla Switch. The Switch is not very accepting of controllers other than the ones designed specifically for the Switch, but the homebrew crowd has done a very good job of fixing that.
Can confirm. Just tried with my newly-Bluetooth'd Stadia controller, will pair with an on-hand Android device and Linux box, doesn't show up on the find controllers screen of an (un-hacked) Switch, as expected.