Natvis is an XML-based description format for types in the debugger. It is supported by windbg.exe and the Visual Studio debugger, at the very least. Visualizations in the debugger are especially helpful for things that are difficult to decode in the debugger (e.g. indexes into a big block of memory are difficult whereas a simple integer is easy). The documentation on natvis is here: https://learn.microsoft.com/en-us/visualstudio/debugger/create-custom-views-of-native-objects?view=vs-2022.

I have been trying to add new usage of rapidyaml to a project that I'm working on and even in debug mode I have not been able to make sense of the ryml types in the debugger.

I had the same problem with rapidjson. However, I just looked and they support natvis. Applying their natvis file to my system was a night and day difference. Their natvis file lives here: https://github.com/Tencent/rapidjson/blob/master/contrib/natvis/rapidjson.natvis.