Unfortunately, like macFUSE, this is not really open source. The license appears to be BSD-like for non-commercial use only. Also like macFUSE, the project uses GitHub but the source code is not available.
Apple is introducing user-space file system technology in macOS – LiveFS/UserFS/com.apple.filesystems.lifs – some of the infrastructure turned up in Monterey, in Ventura it is actually being used for mounting FAT/exFAT filesystems.
It looks like for now Apple is keeping the API Apple-internal only (although I haven't looked at the Ventura SDK, so I could be wrong about that). But if Apple made the API public, it could be the death-knell of all these commercial FUSE-alternatives for macOS offerings. (Even if Apple's API isn't FUSE-compatible, if it is close enough, someone could easily open-source a translation layer – likely to be a lot simpler than bridging FUSE to an NFS server.)
They have the right to use whatever licensing they want, but it is strange that this one area - FUSE on Mac - consistently attracts developers using weird license restrictions.
This is because Google et. al. will take the code and use it unless you do this. (In which case they’ll reimplement it and not pay you, but at least you tried I guess…)
Because the Apple developer culture just like on the Windows side has always been welcoming to commercial software, that is how one keeps a paycheck doing desktop utilities.
Apple is introducing user-space file system technology in macOS – LiveFS/UserFS/com.apple.filesystems.lifs – some of the infrastructure turned up in Monterey, in Ventura it is actually being used for mounting FAT/exFAT filesystems.
It looks like for now Apple is keeping the API Apple-internal only (although I haven't looked at the Ventura SDK, so I could be wrong about that). But if Apple made the API public, it could be the death-knell of all these commercial FUSE-alternatives for macOS offerings. (Even if Apple's API isn't FUSE-compatible, if it is close enough, someone could easily open-source a translation layer – likely to be a lot simpler than bridging FUSE to an NFS server.)