I have a couple of virtual instruments that I am trying use in Ardour6.9.0 on a Mac.
the plugins are:
Arturia Augmented Strings
Spitfire Audio Labs - multiple patches, including Philip Glass’s piano
Both of these will open GUIs in Hosting AU for comparison.
In Ardour, they are detected and you can make a MIDI track with each, but you can only play whatever patch it defaults to…
No GUIs, and no way to change the patches.
I tried both the AU and VST3 versions.