Are you allowed to use Webull and implement limit orders in Canada?

Currently, you are not really allowed to do limit order in Canadian exchanges or in Canada. And yes, you can buy a stock at a lower price than the actual market price. From a discount brokerage platform you can do trade. You can also go for a sell stop order that is generally sold at a lower price than the market tag.

Unfortunately, Webull is currently unavailable in Canada. It is only available to residents in United States, China, the Philippines, India, Korea, Malaysia, Japan, Brazil, and Turkey.

For your second question, only stop-limit orders are allowed in Canadian financial markets. Stop orders are not available on Canadian exchanges.

Also, neither stop nor stop-limit orders are available for Nasdaq Bulletin Board or stocks listed in the Pink Sheet system.