How can I, as a person, talk with my money to prevent this? How can Lockheed Martin, a corporation whose fiduciary obligation is to generate profit for its shareholders, prevent this? How can the US government, who benefits greatly from a prosperous diplomatic relationship with the Monarch, prevent this?
> not caving to them
Fundamentally what I am saying is these institutions are not "caving in" - they are doing what they are doing because, from an emotionless game-theoretical perspective, it is beneficial to the success and longevity of the institution.
Apple benefits from an increasingly strong business relationship (the new diplomacy of the multinational) with mainland China - not just for their supply chain, but also for their marketshare.
These benefits have cost. For US-KSA the cost is tens of thousands of Yemeni civilian lives; for Apple the cost is decreased mindshare of the sovereign nationstate of Taiwan.
With your personal money? You can't. Can you convince extremely wealthy people to spend their money in a way that will ultimately lose them money? Possible, but still losing odds.
See Confessions of an Economic Hitman by John Perkins for an example of what this fight looks like. (he was one of the guys who paved way for the original deals between the US and Saudi Arabia that you mention)
Or, for a far less conspiratorial take on the same phenomenon, read "Globalization and its Discontents" by Nobel Laureate Joseph Stiglitz.
In it you'll learn how institutions like the IMF treated open markets and no currency flow restrictions as a religion regardless of whether they made sense for the stage of development of the countries on which they imposed those as terms of their loans.
Stop buying goods that support these policies. Stop supporting politicians that support these policies. Stop patronizing companies that lobby for these things. Use apps like "Goods Unite Us" to find out where your money is going.
The only way to do anything as an individual is to vote with your wallet, your feet, and your actual vote. When that cumulative change affects the bottom line of these companies, they'll have no choice but to change.