It’s a stretch to think J833ct could be an iMac. The iMac identifiers have been straightforward, two numbers in succession, no letters:
J456 = M1 iMac (Two ports)
J457 = M1 iMac (Four ports)
J433 = Mac15,4 :: M3 iMac (Two ports)
J434 = Mac15,5 :: M3 iMac (Four ports)
J623 = Mac16,2 :: M4 iMac (Two ports)
J624 = Mac16,3 :: M4 iMac (Four ports)
J456 = M1 iMac (Two ports)
J457 = M1 iMac (Four ports)
J433 = Mac15,4 :: M3 iMac (Two ports)
J434 = Mac15,5 :: M3 iMac (Four ports)
J623 = Mac16,2 :: M4 iMac (Two ports)
J624 = Mac16,3 :: M4 iMac (Four ports)