The value of Saudi Aramco can't really be trusted. It's listed on their own stock market which the company controls. It has no reporting requirements, and the float is a single digit percent of the company.
It would be the same as me creating my own market, issuing 10,000,000,000 shares, and then convincing 1000 people to buy a share at $100 and then claiming my company is worth $1T.
I think it's unknowable but most likely overvalued. It is in their best interest to convince everyone that it is more highly valued than it is as they try to diversify. Look at the recent investor gathering they had in Florida. People were desperate to get their attention, even people who have strong political disagreements with them. That only happens because everyone assumes they have a lot of money to invest.
It would be the same as me creating my own market, issuing 10,000,000,000 shares, and then convincing 1000 people to buy a share at $100 and then claiming my company is worth $1T.