I feel like Everwild should be on the Xbox list. While it was announced before Xbox Series X was announced, and hasn't technically been confirmed for Series X yet, it seems to be releasing in 2021, and Microsoft isn't going to release a game on Xbox One but not Series X in 2021.
Same goes for Flight Simulator. While it hasn't technically been confirmed for Series X yet, MS did confirm that it will come to Xbox after it's 2020 PC release, and since MS isn't going to release it on Xbox One only in 2021, a Series X version is pretty much a sure thing.
But I understand if you don't want to add them until they are officially confirmed for Series X, which will surely be at the Xbox July show next month.