I tried the solution in this post https://stackoverflow.com/a/76598533/7904148, on Xcode26 + iOS26 it seems worked for me.

@Developer Tools Engineer I'm having some trouble to use https://developer.apple.com/documentation/xctest/xcuisystem/4108234-open A system dialog "Open in MyApp?" will always show for the first time calling this method, and I couldn't find a way in XCUI to get over this dialog, which basically makes this API not usable. The specific thread for this problem - https://developer.apple.com/forums/thread/730962