Specialized was pretty good about producing NorCal only oddball stuff. Mostly color related, but sometimes bikes too.
I have the exact same bike as the OP but with Mavic wheels (purchased used, 30 clams), I live about 80 miles from San Francisco.
https://www.ebay.com/itm/284264693576
looking at some here, that looks like a standard 6mm flanged cap head allen
flanged
https://www.amazon.com/M6-1-0-Flanged-Button-Socket-Stainless/dp/B07PNZLRY2
unflanged
https://www.amazon.com/M6-1-0-Button-Socket-Stainless-Quantity/dp/B07NDBL185
lol, my feet hit the front wheel on almost all my bikes, doesn't make one's legs longer.
Love your Diamond Back, looks like it's got a Tange Big Fork, basically indestructible.
got flaked on the pickup, (for free even) so I got bored and did this.
It's going to the homeless shelter when complete, they can give it away or sell it or whatever.