All it really takes is Biden having sent his son, and even worse, his son's business partners, ANY e-mails from an official account, pseudonym or not. The content beyond that will just be icing on the cake.
It proves Biden was involved. Content proves some idea of the extent of involvement.
My guess right now is this is going to become an unavoidable shit storm of a disaster for Biden, the Democrats, and Left come about February or March where they are now scrambling to try and find somebody to replace Biden on the presidential ticket as he is clearly badly damaged goods.
Of course, you believe that. You have convinced yourself Trump is a good person and should be president, If you can believe that, you are game for anything. Biden is fine. Trump is in courtrooms across that country. That is the definition of "in trouble'.