well... after literally *years* of searching forums/archives/github off and on trying to figure out if/how @1password's URL scheme is capable of linking to individual items... I finally... figured it out...
in your item's "Private Link," replace (https slash start dot 1password dot com slash) with `onepassword://`.
kindof angry atm lol.
@1password here's a Siri Shortcut for it. https://www.icloud.com/shortcuts/4d816c21922e4f758977ddaa7ea85fcb