> it wasn't clear to me how to find out which packages from the package manager NuGet work on which platforms.
As a default rule, any package you see that targets ".NET Standard 2.0" or ".NET 6+" is using the modern SDK and very likely works across all platforms. This will cover the vast majority of open source packages created/updated in the last 5 years. If a package only specifies '.NET Framework' then it'll be windows-only. Modern packages that are tied to a single platform will likely be named as such and will specify a target that locks it to that platform, ie `net8.0-ios16.0` for iOS.