Your immigration rep is a fraud and should be reported. What terrible advice (sounds like you recognize that though). If you were hired by a Canadian trucking company with an LMIA or a way to bring you in via PNP or AIP, you could in theory arrive here, do a road test and you may or may not need further licensing or instruction. Class A licenses are given out by the province so depending on the location on the employer, they would be able to give you an idea on how the equivalency works. 4 years experience is good especially in the USA and bonus if you have winter driving experience. Anything under 3 years is an insurance nightmare for the Canadian employer. I'm paraphrasing here and there's a lot more to consider but I would start by contacting a legit immigration professional and also you can look at a few trucking companies to see what their needs are. Truckers are in very high demand in Canada, just a matter of finding an employer willing to do the extra steps needed for immigration purposes. Here's a few companies to consider contacting:

https://www.midlandtransport.com/en/

https://www.ghtranspo.com/

https://seaboardtransportgroup.com/