The title says it all! (Just trying to make a guide of the Spiders of Oregon.)
I don’t know of any single source that will show you every species found in North America, filterable by state. SCAN and GBIF are limited to what is listed in collections that have been fully digitized/catalogued - much is missing. OSAC does not have the majority of their collection uploaded to SCAN or otherwise available online. You might reach out to see if they have some type of list available, or someone on staff who can help you.
BugGuide is probably the best general source that will let you filter by state and taxon. It should have most common spiders aside from cryptic/tiny leaflitter-dwelling type things.
Rod Crawford, who you probably know from iNat, made a checklist to the spiders of Washington state (which is mostly similar to Oregon), and RJ Adams’ field guide may have some further useful information to help you compile a list. Sarah Rose’s recent field guide is a great book but may not be of much help beyond the above sources.