The thing with light groups is that it’s a one-and-done situation. You’re lightbulbs don’t change rooms often, do they? It’s just not a high demand need I don’t think. Eventually I’m sure there will be a light group admin UI.
For lovelace UI look for the Folding Group Entity Row Card Folding Group Entity Row Card
For the top level switch / group enter your light group entity.
Then list the sub group / individual entities below it. Really nice UI control for groups and individuals without cluttering everything up.