There are 2 issues with Plugin Importer for iOS/tvOS.
#1. No way to target a plugin to Arm64 Simulator Arch specifically
#2. Arm64 Device plugins are landing in Arm64 Simulator builds(failing to compile Xcode project)

#1 issue
Steps to reproduce :

1. Create new project
2. Switch to iOS/tvOS platform
3. Add native plugin: .dylib .xcframework .framework, .m ... file
4. Plugin importer CPU field should have Arm64 Simulator selection option

Actual results: 
No Arm64 Simulator field available

Expected results: 
Arm64 Simulator field available

#2 issue
Steps to reproduce:
1. Create new project
2. Switch to iOS/tvOS platform
3. Add native plugin: .dylib .xcframework .framework, .m ... file
3.1 set Arm64 architecture ( device )
4. Set Simulator SDK in Player settings
5. Build Xcode project

Actual results: 
Arm64 Plugin for device is included

Expected results: 
Plugin should not be added

Reproducible with versions: 
Unity 6 Beta (6000.0.0b15, build #36011135)
after https://evergreen.ds.unity3d.com/unity/trunk/batch/be07e9a6-3e09-43e0-bab9-a62936ee2394

Not reproducible with versions: 
any version before

Tested on (OS): 
MacBookPro Sonoma 14.2, Unity 6 Beta 6000.0.0f1.5585