The Fusion virtual machine bundle is not using any file system specific features that are problematic for restoring on another platform such as VMware Workstation.
It is also unlikely for VMware to start depend on such a file system specific feature as it would mean problems for their own cross platform approach.
You can bring your Fusion VM to Workstation or even vSphere and provided you use the correct virtual disk format it will mostly just work.
FWIW, the virtual machine backup program I developed (Vimalin see my signature for more info) does offer your request as a feature.
You can restore a Fusion VM on VMware Workstation Professional as you can import backups made by either product and Vimalin will handle the restore.
Oh I forgot, the easiest way to do this is not by reading directly from an attached disk and file system but by using network shares.
Nowadays macOS can read/write quite well on SMB network shares. If you're uncomfortable by that then you can present a share both as NFS for macOS and as SMB for Windows.
Hope this helps,
Wil| Author of Vimalin. The virtual machine Backup app for VMware Desktop Products
| Vimalin : Automated backups for VMware Fusion and VMware Workstation Professional
| More info at https://www.vimalin.com
| Twitter @wilva
| VMware Wiki at http://www.vi-toolkit.com
Just to expand on Wila's comments, there's no mac-specific formatting at all. You just end up with a folder with an extension if you copy the bundle to an external drive (exfat formatted for example) and then plug that into a windows box. In fact, you can remove the .vmwarevm extension and just hold the files in a folder on OSX as well (not recommended though, the extension keeps things tidy. There's no real need to do anything with sparsebundles to back up the VM.
The only caveats are 1) that if it's an OSX guest, it'll only work on Apple hardware, and 2) make sure that the VM is shut down, not suspended, before backing it up and/or trying to open it in Workstation. Likewise, deleting any snapshots that were made while the VM is running is also necessary.