This GJ thread has perhaps the most in-depth discussion of Filson tools. I started the thread after discovering the article mentioned in it that shed some important light on the brand:
https://www.garagejournal.com/forum/showthread.php?t=385635
It was generally believe that Filson was just a brand name that contracted its tools from other mfrs. The article finally demonstrated that Filson indeed made at least some of its own tools, particularly wrenches. We have evidence, however, that it contracted out its ratchets.
Acquiring a collection will be a challenge. No one here is really sure as to the extent of the company's tool line. It does not appear to have been a major player in the market, so Filson branded tools are relegated to the occasional odd find at a yard sale or flea market. Also, within the artifacts found, there is a significant variety of designs, making it look almost as if the company produced a run of its own tools each time it had a contract set of dies for another brand. And so we still don't know all of what it made, when and in what style.
Good luck with your efforts, and please keep us posted.
BTW, this thread should be more properly posted in the Vintage Tool section where you'll find the group dedicated to the old tools. This General Section is more focused on today's tools and today's work being done with them.