This is not my field, but IIRC dilution refrigerators capable of sub-K temperatures are nowadays available off the shelf from a number of commercial suppliers. Which is a pretty cool (har har!) advance considering not many decades ago labs had to create their own, at great expense.

So in principle, there might not be any really fundamental issues preventing such things in every home, with mass production economies making them cheaper and more reliable.

The real question IMHO is whether this will be useful in some way compared to just connecting over the internet to some data center running them.

Safety is a fundamental issue. Home appliances don't get the best maintenance available, and supercool and high-pressure containers aren't easy to keep around.