These are all standard ARM instructions. Apple tweaks the semantics of some of them in Rosetta mode to better support what they’re doing but it’s otherwise not involving any new encodings.
As named, the extensions called ‘Apple’s secret extension’ are not standard, they are Apple specific and it’s not just ‘tweak the semantics’, it’s custom and only turned on for Rosetta 2 because otherwise they would cause unexpected results for software expediting normal ARM behavior.
arm64 + special proprietary bits = 'Apple Assembly', or whatever marketing name, seems within the realm of possibility.
It wouldn't be that much of an outlier in terms of naming convention.
Not a single developer facing product is called Apple anything.