What constitutes "from the legislature"? Surely it is more than a subset of partisan players who meet in private and then sign a document. Perhaps if it is a matter introduced and debated in the legislature, according to the constitution of the state, and then passed in both chambers of the state legislature....then it could be potentially considered as a duelling electoral slate from the state legislature. Even then, there are questions as to what safe harbor provisions actually mean in determining which slate to accept. Nevertheless, under that hypothetical scenario the question as to whether the VP has any powers to choose become non moot.
However, given that the so called competing slates that you are hanging so much on, do not remotely meet that criteria, I would say the chances of Pence playing anything other than a ceremonial role in the confirmation of a Biden presidency, are close to zero. Unless of course, he absconds and leaves it to the president pro tempore.
