I would like to be able to select the same “brand color” on all “color variables” and then keep the transparency to be modifiable.

Exact same use case for me. We too work with “brand colors” (our product is a white label). To achieve depth and movement in the design we constantly use different transparency levels of the brand color.

It is a very tedious job to manually change every layer with a different transparency, so we usually build components in a way that we only need to change a single color in the selection colors section (or mode with variables), but this often requires an extra layer of overlays or filters which are not very easy to maintain and add a layer of complexity when handing off to dev (since in dev mode they only see the fill of what’s selected and this workaround requires two layers to achieve desired effect).

Exactly this!

Exact same use case for me.