Recently moved to Canada from the US and we were not able to open bank accounts (tried TD and Tangerine) without SIN. Since we were quarantining, we applied for SIN online and it took 2 weeks for it to arrive by mail.
If ServiceCanada at airport isn't operating or you are not starting a new job while quarantining, I would suggest waiting for the quarantine to be over to visit ServiceCanada in person to get SIN. They provide you with SIN on the spot if you visit the office in person.
also, try to schedule an appointment with one of the banks for sometime soon after your quarantine ends. We were able to open accounts online soon after receiving SIN but our accounts were blocked till we visited the branch to get COPR and passports verified by an agent.