There's a VFS layer in pretty much every commercially viable *ix OS today via Unix, plus many other FOSS projects with file system abstraction features: * Solaris at least back to [2005's OpenSolaris release](https://github.com/illumos/illumos-gate/blob/master/usr/src/uts/common/fs/vfs.c) ([more details](https://docs.oracle.com/cd/E19455-01/805-6331/6j5vgg68e/index.html)) * [FreeBSD since 1996](https://svnweb.freebsd.org/base/head/sys/kern/vfs_init.c?revision=14499&view=markup) as "VFS", and back into 4.4BSD as just the "FS" layer. * [macOS via FreeBSD](https://opensource.apple.com/source/xnu/xnu-1699.32.7/bsd/vfs/vfs_init.c.auto.html) * [Linux](https://www.kernel.org/doc/html/latest/filesystems/vfs.html) * [GNOME](https://developer.gnome.org/gnome-vfs/) * [Samba](https://wiki.samba.org/index.php/Virtual_File_System_Modules) * [others](https://en.wikipedia.org/wiki/Virtual_file_system)