My friend just dealt with this over the last few days (from Canada). He couldn't enter through land because of a Biden EO. He could enter through air because that EO doesn't apply to air travel. As far as airline checks, it might depend on the airline and whether they have restrictions, I think he used air canada. But I don't think there's any EO or law as of now that requires airlines to check vax status (as far as I know).
My friend just dealt with this over the last few days (from Canada). He couldn't enter through land because of a Biden EO. He could enter through air because that EO doesn't apply to air travel. As far as airline checks, it might depend on the airline and whether they have restrictions, I think he used air canada. But I don't think there's any EO or law as of now that requires airlines to check vax status (as far as I know).