To check I did this: removed the signature (LC_CODE_SIGNATURE section) using lief Python package (no affiliation, just looked suitable for the task), checked by otool that the section is indeed gone, started the binary - it worked. The spctl said that the binary is "rejected", but it says so about every non-Apple binary I checked on my machine so not informative. The codesign tool shows "is not signed at all" on the binary with stripped signature.
I'm not too well-versed in OSX system/dev tools, so if there is a more correct/precise method of checking the signatures I'd very much like to know.
Nope, 15.7.2. Maybe there are some settings, unknown to me, that are configured by MDM and that allow for such behaviour - our Macbooks are managed by the employer and are intended for development, so would be logical to set them up this way.
_A Mac with Apple silicon doesn’t permit native arm64 code to execute unless a valid signature is attached. This signature can be as simple as an ad hoc code signature (cf. codesign(1)) that doesn’t bear any actual identity from the secret half of an asymmetric key pair (it’s simply an unauthenticated measurement of the binary)._
_For binary compatibility, translated x86_64 code is permitted to execute through Rosetta with no signature information at all. No specific identity is conveyed to this code through the device-specific Secure Enclave signing procedure, and it executes with precisely the same limitations as native unsigned code executing on an Intel-based Mac._