No, Steam is not the primary PC release either.
Ubisoft has its own launcher, UbiConnect.
Steams does not represent even the entirety of the PC sales.
EDIT: This does not mean I believe the game will be a commercial success. Just that Steam player/peak numbers are useless. We do not know how many actual copies of the game were sold and we will only find out when the investors are told, which could be as late as July for the annual conference. Until then Ubislop will try to frame the numbers they publish in as positive a light as they can to attract more players.
I think as was mentioned before players != Sales, which is to say we don't know how many of these were free codes given with hardware or promo codes for people who they want to have the game, game reviewers, etc.
Not to mention in terms of giants like Ubisoft, EA, 1 million is peanuts, Veilguard gloated with the same message after about 1 week and have since then stranded on around 1.55 million sales before it went to the dollar bin.
In the words of their own CFO, Frederick Duguet, they need around 8 to 10 million to break even for high budget AAA games, AC being their flagship game this is more than likely the case especially including the months of delays.
Unfortunately taking extra time to polish a turd does nothing to mask the smell, and I highly doubt they will break even on this specific turd.
In this case I believe you mentioned before, breaking even will not suffice to fill the gap from their last FY, time will tell but I think this is nothing different than how Veilguard went, they got people to make a lot of noise around the game but most people aren't listening either way or have a (righteous) rage boner towards the game and Ubisoft's practices.
Sell the IP to Asian chuds and hope for better titles in the future, though this is a very optimistic outlook AFAIK