Splatoon 2 on Switch uses peer to peer for online games. Nintendo do seem to have implemented regional matchmaking but the servers they use to control how is in a game seem to be based in the US and Japan. Therefore, I seem to need to keep the geo filter wide to allow connection to the servers and rely on the ping assist to filter out laggy players. However, occasionally players from US and Japan will appear so would be nice to be able to use Geo Filter to keep them at bay. I could whitelist the Nintendo servers but there does seem to be a lot of them.
On a related matter, when creating a service for my Nintendo Switch the only option is Wii Online. Is that the same as the Nintendo network or is a revised service profile required?