I'm not certain on that...
On private medical issues, it is my understanding that Biden has full control of what can and can not be released. Biden or Trump etc can release some medical information like the basics and hold other crud back...it's happened with darn near every president...including Trump, when he was a hair from dying of Covid....we weren't told it was that bad, then Kennedy and his ailments, and FDR and his disability, etc....
None of that is illegal, though I agree it is stuff we would like to know and should be told...it simply is not in our power or Congress's power, to force Biden to give up his right to privacy that his doctor is obligated to honor.
There is no criminality involved, his doctor can not be forced by congress to "tell all" against his patient's will.
This is a performance by the Republican Congress Critters, a Dog and Pony show, and that is clear as day...imo.
The Critters know the Doc can't answer their questions and know he wouldn't... YET........ YET they had their hearing anyway....wasting the tax payer's dime....when they would likely get more info from those around him or maybe Jill....? Shoot, Jake Tapper got more info on Biden's condition than most all of us knew a fraction of....just by interviewing leg work....