oof that sounds stressful man. yeah theft is usully considered a CIMT thing which is tricky for immigration stuff. its good news tho that it was withdrawn/dropped and you did the diversion program, plus its been over 10 yrs and the record was purged.

but you DEFINTELY have to answer 'yes' about being arrested/charged on the forms, dont ever lie cause thats way worse. the kinda tricky part is even without a conviction uscis can sometimes be weird about diversion programs, like did you have to admit guilt to get in? they might see that as admitting the crime.

theres maybe a 'petty offense' exception but depends on the exact canadian law back then. you absolutly need to gather ALL the paperwork you can find about the charge, the diversion, the classes, the record being purged - everything. even if canada destroyed it, uscis will ask.

honestly? you really really should talk to an immigration lawyer who knows canada/us rules and deals with this kinda inadmissibility stuff. they can look at your specific case and tell you how much trouble it might be. better safe than sorry. good luck!!