I'm interested to know more about this. Can you provide more details?

TSMC is building significant, cutting-edge fab capacity in the US at present

It's very, very unclear to me what would happen to TSMC's American operations if China invades/seizes/blockades Taiwan.

How independent would TSMC's American foundries be if cut off and forced to operate autonomously if US/China war breaks out?

I am sure that the goal is full independence but I have no idea what the current state of that is, what the state of it will be in 5-10 years etc.

Is it cost effective or logistically scalable to have the kinds of ICs that are used in current cheap FPV drones to be made on the latest fabs?

Well the US has a ton of larger process size fabs. There's at least 100 fabs of varying sizes and processes in the US as well as internal supply chain for materials, testing, and assembly. (Where do you think most of the semiconductors containing classified designs are manufactured)

Most are much smaller and more specialised/less automated so they don't have the same kind of production but there are a lot of fabs in the US and a lot of fab knowledge. Of all the countries, the US is one of the few that could probably survive a semiconductor industry collapse outside.

And many of those semiconductors in cheap FPV drones likely are actually fabbed in the US or could easily be fabbed in the US by Intel, Infineon, Texas Instruments, pSemi, NXP, Bosch, Renesas, Micron, onsemi, Analog Devices, Honeywell, Polar, GlobalFoundaries, Microchip, or Samsung, just to name a few non-military facing companies with significant fab operations in the US.