I was having the same problem—no native arm64 simulators were showing up at all for the iOS 26. As a desperate move to try and get any simulator to work, I downloaded an older iOS runtime, but even those only appeared in my list labeled as (Rosetta).

That's when I found this. Removing arm64 from Build Settings > Excluded Architectures fixed it immediately.

It's likely that newer versions of Xcode (like 26) only download the native arm64 simulator runtime by default, and not the older Intel x86_64 one.

My project, with that old build setting, and stop forcing the Intel build, I'm assuming @Fourth's suggestion to run xcodebuild -downloadPlatform iOS -architectureVariant universal would also work by forcing Xcode to download all the runtimes.