The Web versions also consume C++ via WebAssembly, the mobile versions are a mix of the platform languages + C++.
There are some CppCon talks about how they use C++ in Office.
Where do I start? Do you have a compiled version of some information on this?
Since I know those languages since 1992, and have coded for Windows since Windows 3.0, I never bothered with any guide personally.
I hate to say but GitHub Copilot can get you started. It slurped up all of Microsoft SDK and docs and open source libs. It is a decent reference.
I'm also kinda impressed by the Debugger Agent [0] built into Visual Studio 2026.
[0] https://medium.com/@onu.khatri/copilot-squad-in-vs-2026-ca88...
In a complicated Excel sheet I had the Conditional Formatting Rules Magaer crash due to an issue in EmbeddedWebView2.dll. Renaming it helped preventing the crash without obvious decline in functionality in Excel, until I tried to join a Teams meeting which obviously uses WebView2.