Steam on Linux provides a fixed target set of libraries because it’s kind of hard to release native games on Linux (you have to include a crapload of libraries you expect to be installed otherwise, which Steam solves).
Larian is essentially styling now. Even Valve doesn’t release native ports anymore and went as far as removing some in favour of Proton versions.
I assume that it’s an offer to use their fabs. Doubt that Apple believes Intel’s roadmaps given their history.