I’ve had exotic armour ornaments drop. However not any of the legendary armour ornaments that are sold for silver.

I imagine this still works, though I haven't tried. In you inventory, where it shows engrams you haven't redeemed, you can inspect bright ones and it'll tell you what can drop from it. I've gotten some weapon ornaments from Season of Opulence, so I'm guessing it might include the Armor ornament from then as well.