I don't think any of these companies use Rust much. You may find teams here and there using it but the vast majority of the Rust type stuff is written in C++ or Java.
It depends on what you mean by "much." If you mean "as a volume of LOC of total software development," absolutely. But if you mean "not being used for anything big" or "not being used for anything important," that is very much wrong.
In what concerns Microsoft, I am yet to see anything besides Win32 and WinRT bindings generation.
UWP/WinUI foundations are in C++ and .NET.
Azure Sphere, despite all the security selling marketing uses C based SDK.
Windows kernel seemed to be in the right direction adopting more C++ and less C, specially with the userspace drivers COM SDK, but they just reverted to more C support on the latest versions.
So in what concerns Microsoft, I look forward to their Rust's adoption, although currently its adoption is yet to be reflected on the Windows development ecosystem.
