> The ones that aren't embedded in someway and use industrial grade PCs/control stations? Or ones with large buffers like network routers?

Not sure if they require DDR5 but the AI crisis just caused the prices of DDR5 to rise but the market supply of DDR4 thus grew and that's why they got more expensive too

> I'm also wondering about the supply of the alternate nodes and older technologies.

I suppose these might be chinese companies but there might be some european/american companies (not sure) but if things continue, there is gonna be a strain on them in demand and they might increase their prices too

> Was it micron that abandoned the entire retail market in favor of supplying the hyperscalers?

Yes