It's not a full-blown userspace filesystem like fuse or dokany (which already has a fuse wrapper). The projected file system still needs a local folder where it can place copies of files from the "backing store". E.g note the Remarks section at https://learn.microsoft.com/en-us/windows/win32/api/projecte...

> When ProjFS receives the data it will write it to the file to convert it into a hydrated placeholder.

There's some discussion here: https://github.com/microsoft/ProjFS-Managed-API/issues/54

It looks like it's meant to solve a much narrower problem than FUSE.

Edit:

Since you mentioned Dokany[0] I'll also throw out a shout for WinFsp[1] as a similar project, too.

[0] https://github.com/dokan-dev/dokany

[1] https://winfsp.dev/

oh, I had no idea from scanning the docs that it created a physical file for every virtual file. that really makes it of marginal general use.

I suppose the choice of the name also makes sense in that context.