If the Qt on which Dorico is based (to make it more transportable) is not yet ARM ready, Dorico may have to wait (lobbying Qt, I’m sure for that support) for Qt to change.
If VST support for ARM is possible for other Steinberg products, it is hard to believe that Dorico would not support them unless there are differences that must still be addressed by an admittedly small group of programmers with multiple program enhancements to consider. As Dorico never announces program features in advance, it is not surprising that you received no promise of rapid adoption.
I hope Dorico will soon announce a version that helps you use Dorico on your ARM computers.