If you got Unified Theory and Trick Magic Item (Arcana) could you use magic items from other spell casters.
EX – Scrolls, Wands, and Staves
indigochild said on this post that
(Does the "Unified Theory" skill feat have any interaction with the "Natural Medicine" skill feat?)
"That you are using an action or skill feat.
That whatever you are doing requires a Nature, Occultism, or Religion check.
That the kind of check is determined by a magical tradition."
Unified Theory https://2e.aonprd.com/Feats.aspx?ID=859
Trick Magic Item https://2e.aonprd.com/Feats.aspx?ID=857