The same condition is still true as the first time I was told "Swift on Linux" is somehow a first class experience:
> Documentation for the standard library is presently hosted on the Apple Developer website.
Sure enough, by Apple policy, the documentation pretends no non-Apple platforms exist. What happens for an API which could be different if your system isn't fruit-flavoured? They don't care and won't talk about it.
Is the feature I need available for this Linux device? No idea, but it does work with watchOS and tvOS made by Apple...
> Is the feature I need available for this Linux device?
If it’s in Foundation, yes. Swift 6 on Apple OSes now (since a while ago actually) uses the same open-source foundation as Linux. If it’s a proprietary framework (e.g. TabularData), no. It’s simple.
For the rest, almost all Swift packages developed by Apple are fully compatible with Linux, and the documentation of said packages is usually explicit wrt. platform specifics, AFAIK.