Exploring Major CTV SSP Players in Canada for Publishers Transitioning from DOOH

I come from the DOOH space, working on the publisher/operator side, and recently I've started to delve into the Connected TV (CTV) arena. I'm curious to know the landscape of major SSPs in Canada for a publisher looking to partner. In the DOOH sector, we've seen significant engagement with platforms like Hivestack and Vistar, and to a lesser extent, Broadsign and PlaceExchange. Who are the key players in the CTV SSP world that mirror these platforms? Any insights or advice on integrating with these SSPs would be greatly appreciated.