Send MIDI to external hardware also for Audio Units (AU) not for VST only

as a UAD Luna DAW user, I’m limited to AU only as it doesn’t take VST at all.
It would be great to also have the ability to send midi notes from scalar directly to my external hardware gear.

You can use something like Blue Cat Patchwork to host VST inside Luna.
You should also speak to UAD about adding VST for this sort of thing. There are some other hosts available for this as well that work.
Apple is working on specs for AU3 so talking to them would help move forward on this issue.