The selection is a function of State Legislatures, and, like it or not, the State Legislatures of Pennsylvania, Michigan, Wisconsin, Georgia, and Arizona have either appointed or consented through inaction to the appointment of, 73 Electors who intended to vote for Biden and Harris.
These are legally appointed, the only entity with a right to object are those Legislatures, which they show ABSOLUTELY NO sign of doing.
IF (for example) the Pennsylvania Legislature voted by majorities in both Houses to sue the Secretary of State and the Governor, they could possibly have a Federal case that those officials have breached the Article II electors clause.
But no one else has that right. There are no "Presidential elections" in the Constitution, there is no right to "vote for President" (unless you are one of the 538 Electors), and any arguments about Pence or the military must account for WHY the Legislatures, whose right the appointment of Electors is in the first place, are not objecting.
These electors are fruit of the poisonous tree, the proverbial “bad apples”.