Hi there OP, if you are interested in and/or have access to modding on PC there is a mod that allows for changing Origins' appearance. There are limits to Wyll specifically due to his personal quest (no spoilers *grin*)

As far as the possibility for Larian allowing Origin changes via Magic Mirror--the community in general has been requesting this change but it's a delicious mystery as to if Larian will provide.
(I'm toooottttallly on your side btw. I feel it's a goofy restriction that we can't change hair style, make up, earrings when we play as Origins _and_ when they are companions in our Tav/Durge runs)

The mod is here

https://www.nexusmods.com/baldursgate3/mods/899

Best wishes!
*grin*