On the device side, this could be done by adding an additional Switch Ring Color entry dynamically if Scene - Toggle is selected.
Problem here would be the positioning: since the entry for the switch ring color is on top, selecting Scene - Toggle for either Tap or Hold would add an entry above, which would cause "jumping" in the layout.
For this, I would propose to add a permanent second option (Toggle Switch Ring Color), which can be set to "as primary color" or the additional second option color. If you select a setting which doesn’t support toggling, the option may be set to „as primary Color“ on leaving the selection screen to create consistency (and I don’t think that anybody would expect an option which is not used to be remembered).
This way, it is clear that this color option is only active if a setting with toggling is available.
This setting could be also reused for Bank - Toggle, Preset - Toggle and Effect -Toggle, and would have no effect on Utility, Layout and View options.