One can use SharpShell for this to do it in C#. Development and deployment remain unwieldy though.
Has that changed by now?
[0] https://devblogs.microsoft.com/oldnewthing/20061218-01/?p=28...
https://docs.microsoft.com/en-us/archive/msdn-magazine/2009/...
Also note that Windows development team doesn't have that much .NET love (owned by DevTools).
The advice is still "don't use .NET managed code for your in-proc shell extension", but the given reasons are not necessarily specific to the .NET runtime:
1. The .NET framework CLR takes too long to load for an extension that could be loaded by any app that pops up shell UIs.
2. There are seams between .NET and COM even with interop. These seams open traps for you because the COM-era shell APIs (Windows 95 to Windows 7) were designed for people who write their shell extensions in C++ and so can deal with all the tricky details of COM.