The wirsbo pex is for expanding and inserting the wirsbo fittings. It is IMO the best system out there.
Because it is an SDR-9 tube you could use other fittings with it such as crimp ring fittings and they will fit and work. However, the wirsbo warrantee on the tubing would be reduced, warrantee on the fittings from the other manufacturer would be whatever their guarantee states when used with someone elses tubing.
Can you? Yes in many cases.
Should you? probably not.