I myself am 100ish hours into AC Odyssey on the Steam Deck, looking forward to getting stabby on some malakas!
Well, it’s always multiplayer, meaning you will see people out in the world constantly. A lot of content (like dungeons) is instanced to your party, though, so you won’t see randoms where it really matters. Personally, I have only played solo so far except for the aforementioned randoms :). I’m sure it would be very fun with others, though!