Xcode 27. Technically I think I have my apps ready to go with 27.1 (plus other fixes) but since previews in Xcode don't work properly for the Duo (and that is where all my mock data is that I check my UI with) I'm holding off a bit to see if Apple gets that fixed before submitting my app updates.
Device Hub is better, but… no mock data and I don't really feel like trying to recreate all of my mock data by hand when I went through all that work to get it set up in previews so I could see at-a-glance if something isn't working correctly.