Just E3 2017. The Switch presentation opened with 1-2 Switch, which was followed by ARMS, then I believe it went Splatoon 2 and Odyssey before Xenoblade 2. That's just the games portion though, they actually opened with a hardware trailer followed by info.Didnt we have an E3 and the Switch reveal event both open with Monolith Soft games?
E3 2018 featured Torna as the first Nintendo game, but they actually opened with Daemon X Machina (which Nintendo did publish on Switch if you want to count it as Nintendo). Many of us were wondering if that was by Monolith Soft for a second though.