It would be useful if the automatic underscores also worked for Greek letters, such that when there is a \alpha and I type 1 not \alpha1 but \alpha_1 appears.

(This would be useful, but TBH if this is not easily doable, I would prioritize #30 over this, because this is just a feature, which would make this package more useful/better, the other one is a bug, which makes it unusable, for people, who are working a lot with siunitx/chemical environments.)