How do I generate a static site for multiple API versions and multiple combinations of predefined symbols (preprocessor directives) with Unity?

[GarfieldJiang]

I'm working on the documentation of a Unity project (in-company use for other projects). Now I've passed the basic part of generating a site of docs from source code (since dotnet isn't able to restore Unity generated .csproj files). And I'm a bit lost when I look further.

For each API version, I got serveral different predefined symbol combinations (metadata[i].properties.DefineConstants). I wanna output the UNION SET of all the apis. It seems there is a merge feature which is broken?

Besides, it'd be better if I can make all my release versions (like 1.0, 1.1, 2.0, 3.0, ...) use the same static site.

How should I achieve these? Thanks.