We have an old implementation of this here that was written before Go's fs.FS interface.
This needs to be updated for UFS 1.5 and since we're no longer directly within go-ipfs, we'll need to update it to use the client APIs.

Last time I checked, the API does not allow overwriting the root node like we could do before. I think we'll also have to do synchronization manually (instead of being able to pass in a callback that's triggered on modifications).

With these limitations, I'm thinking about just creating a mount subdirectory within the MFS root, and treating that as our mutable root instead of the actual root (since we can't tell the IPFS node to replace it as-is). Maybe allowing this to be changed with parameters so that users can mount arbitrary directories within the MFS root.