Having this capability would be extremely nice.
A single .msi targeting x64 and ARM64 is becoming a hot requirement, at least for me.
A part of our installation is x64, even on the ARM64. And we use custom actions to call into out x64 DLLs during uninstall, etc.
As is, the custom action 'call function in a dll' doesn't work on ARM64 systems. It appears that native ARM64 code invoked by AI is trying to load our x64 DLL. And that will not work, of course.
So we are forced to come up with ugly workarounds using powershell scripts that determine if we are running on ARM64 and force launching of the x64 version of powershell. The PS script then loads a DLL and calls a function in it (there is an example of this on the AI support site).
Very ugly. Especially when a value from a DLL function needs to be stored into the installer properties.
So, adding the 'ARM64' checkbox in addition to the '64 bit' in the parameters for the 'call function in a DLL' custom action would be a great feature for AI.