There exists domestic supply, it's just not scaled up:

https://www.goodram.com/en/

You don't see their products in stores too often as they're focused on B2B - particularly the automotive sector.

That being said I have a 128GB memory stick from this manufacturer and I hope they make the most out of this windfall.

I'm pretty sure they're just assembling DIMMs (and SSDs), not fabricating the memory ICs on it. The latter are what are in short supply.

Thats assembly, couple lanes of PCB Reflow ovens. They have been at this since mid nineties, always offering lifetime ram warranty too. Ram and SSD pretty commonly seen in retail.