The Founders' greatest fear, when it came to the president, was that a man would be installed in the office who was in debt to, or loyal to a foreign government. It's why they put the Foreign Emoluments ban in the Constitution.
Jared Kushner visited with the Saudi's and the UAE just before they blockaded Qatar; within a few months an investment fund heavily financed by Qatar gave Kushner the billion dollars he desperately needed to save his failing real estate empire, and the blockade ended.
Trump also helped prevent efforts to hold Saudi dictator MBS responsible for his murdering Jamal Khashoggi, and stabbed the Syrian Kurds in the back when Turkey's president told him to. Trump, of course, makes millions from his properties in Turkey.
Now, Trump is about to leave office with debts exceeding $1 billion, over $400 million of them personally guaranteed. So, what does he have or know that a foreign government might be willing to pay him $1 billion for?
Since his only loyalties are to himself, the question becomes what do they want and what will they pay? I am sure the price will be right.