Didn't the Habsburg/Valois conflict only really started once Mary and Maximilian were engaged? Frederick III and Charles the bold weren't allies (the emperor was affraid of the Burgundian advances along the Rhine) and the marriage between their heirs was made mostly because of the possibility of securing the huge Burgundian inheritance to the Habsburg dynasty. If Mary is a boy then Frederick would have no reason to enter in conflict with the French.
Yes this is important. Most of Charles the Bold's political maneuvering was based around his daughter. He dangled her as a marriage prospect to the French dauphin, the Duke of Berry (a thorn in Louis XI's side), the Duke of Lorraine (whose territory lay between Burgundy and the Low Countries) and the Habsburgs. Part of the reason any of these people were willing to concede anything to Charles or render any aide to his cause was because the prospect of inheriting his lands was so tempting. So the diplomatic calculus is completely upended with a male heir.
I think it also could change Charles' outlook. His greatest ambition OTL became gaining the Imperial Crown. While he did pursue a Royal crown he ultimately wanted to be made King of the Romans and then Emperor. I've always wondered to what extent this comes from a sense that he was the end of the line anyways so he might as well leverage his position for personal power or glory. In other words I wonder if just maybe with a male son Charles' would be more concerned with his legacy, the integrity of his dynasty and the accumulation of lands, wealth and power that could be passed on to his son. This again would dramatically change the way his reign unfolds which in turn would change the contemporary western European politics unfolds.
But even if it doesn't change Charles' character or strategic goals a male child would certainly change his options for achieving them so it would quickly set him on a very different course. So I think there would be more immediate changes, ones just as profound as guessing who a male heir might marry. The butterflies multiply exponentially from there.