I have scoured the internet, and far as I can tell, that alleged content of Ashley Biden's diary, has only been reported by far right sites with little credibility.
They include :
1) National File - a right-wing blog and news website, founded in August of 2019. They are best known for publishing false and misleading claims about COVID-19.
2) Project Veritas - a far right activist group, which produces deceptively edited videos of its undercover operations, which use secret recordings in an effort to discredit mainstream media. They have proven themselves to not be above lying.
3) The Gateway Pundit - a far right fake news site, which is known for publishing falsehoods, hoaxes, and conspiracy theories.
I don't buy it. It looks too much like PizzaGate to me.