An interesting initiative has been launched by a Nintendo fan. This particular fan has set up a site called Switcher.gg, which facilitates meet ups for Switch owners for local multiplayer games. In order to get started, you simply register via email or Discord.
Once connected, you will be able to search for nearby players, filter based on distance from you, for co-op or PvP games. You're also able to post your Nintendo-ID and what games you play.
Clearly, the success of the site rides on the number of players who make use of it, because unless there are lots of players registered, you'll have a hard time finding people to meet up with near you.
It's an interesting attempt as local multiplayer on Nintendo's handhelds has been something that mainly happens in Japan, where it's normal, and there have been many games for 3DS that relied heavily on local multiplayer and therefore didn't really succeed in the West.
Is this something that interests you or are you more inclined to play online or locally with people you already know?