Direct answer
Ontario's electronics regulation doesn't make a company register with RPRA for retiring office equipment it bought for its own use, and it doesn't order that company to pick a registered provider. That holds while the company is only an end user, not also a producer or a service provider. The duty sits with the provider. Under O. Reg. 522/20, the business that arranges to haul your used equipment and the business that processes it must each register with the Resource Productivity and Recovery Authority. So the practical answer is yes for those two roles. A hauler or processor has 30 days from its first load to register, so an established vendor that hasn't registered after that deadline has missed a duty that applies to it. You can start the check in a few minutes on RPRA's public lists.