I think white space in file names was possible in Unix long before Windows. IIRC...

dhosek on Oct 24, 2022 | parent | context | favorite | on: How Rust 1.64 became faster on Windows

I think white space in file names was possible in Unix long before Windows. IIRC, VMS and (probably TOPS-10/20) did not allow white space. It may have also been possible to include spaces in DOS file names, but it’s long enough ago, that I wouldn’t be completely sure of it.