Trump is simply using the old standard:
“Promise her ANYTHING but give her Arpege.”
It’s to humor the mainland Chinese only but does not reflect the realities on the ground. It’s been the American approach for a long time. Trump has bigger fish to fry at the moment and doesn’t need distractions.
“US arms sales to Taiwan are guided by the Taiwan Relations Act and based on an assessment of Taiwan’s defense needs.”
It looks like you are correct by the above statement. I’m sure we have trade agreements, etc. with Taiwan as well. OCINO. (One China in name only!).