The only bikes called OSSAs sold in the 2000s were trials bikes and a long-ride variant of the trials bike. They are not OSSAs in the way that a Super Pioneer is an OSSA. The original OSSA company went out of business in the early 1980s.
The more recent "OSSAs" were made by a new company who used OSSA badging to try and take advantage of brand loyalty that has carried on since the 1970s. The company that made the recent "OSSA"s got into financial difficulties after a couple of years of manufacture and was bought out by one of the more established trials bike manufacturers who has not made any "OSSA"s