Well. Not so fast. It isn't cynicism to point out issues with this idea.
You can't accept half a million random tests kits and use them for anything. It isn't that simple. At a minimum, we know nothing about where they came from, their traceability, method of manufacture, sterility, etc. And then there's the reality that "test kits" does not mean swab-to-result technology. There's a lot more to testing someone for, well, anything, than the mere extraction or collection of a sample.
Extreme example, ten million blood test vials are useless if their manufacturing and quality isn't traceable and you don't have the chemistry needed to run blood analysis with them.
Same with the million face masks. China isn't necessarily known for top quality manufacturing except for where external companies (Apple) put in massive process controls and supervision. Same issue here with masks. I would not trust them as far as I could throw them.
This isn't being negative. It's reality. If you've ever manufactured anything in China you understand very well how careful you have to be not to end-up with junk. Sure, there are great factories and engineers there, but, to use the phrase, you have to trust but verify.
That said, nice gesture. Yet, no, I would not touch any of that stuff unless our authorities can ascertain their quality and safety 100%.
Our private enterprises are spinning up manufacturing of all of these items fast. I would much rather trust them. Sorry, but we need to start to decouple from China to the extent possible. If Europe and North America can't make their own masks and medical supplies we might as well hand over the keys and call it a good run.
EDIT: Personal example about Chinese manufacturing as a consumer (I have plenty more stories as a manufacturer):
We bought a jacuzzi tub directly from China. Alibaba, in fact. After much research we found the factory that make these tubs for everyone. By this I mean, they make them and companies like Whirlpool in the US put their logo on it. So, we bought one. Given that I understand the issues with Chinese manufacturing due to personal experience, the first thing I did when we got it was take it apart and test absolutely everything.
This thing had almost every defect in the book. It had leaks. It had loose washers inside the electronics enclosure. It had copper wire strands in there as well. The screws on the barrier strip for the 120V in and out connections were lose. And a ground connection was missing. Without spending several hours fixing it, this thing would have leaked water and soap everywhere, shorted out, burned out and maybe even electrocuted someone.
So, yeah, trust but verify. Everything.
And, yeah #2, the people down-voting this have no clue whatsoever about the realities of manufacturing in China without serious and extensive controls.
Ignorance is bliss.