The complete 1931 census of Canada, with copious details of interest to historical researchers, genealogists, and many others, was released to Library and Archives Canada June 1, 2023. It's available.
But it's not yet available available.
You cannot yet put in a name and have the data pop up, either on Library and Archives Canada web presence or at online commercial services such as Ancestry.ca. That will first require completion of a lot of digitizing and organizing. Involvement of the commercial services in this process will speed the process beyond what the LAC budget would permit.
LAC has posted and is updating a pretty good state-of-progress page on the making-available of the 1931 data. Pending the digitizing process, you cannot yet search Grannie's census data just by typing her name in a search box. Did she own a radio? That was a new question on the 1931 census.
You can now look at any particular page of the census as filled in by the census-taker. But, for the time being, you need to know the province, district, sub-district and so on in which a persons in whom you are interested lived in 1931.
LAC hopes that as early as this fall users will be able to run digital searches by name using the LAC Census Search. And presumably in the participating commercial genealogy sites too.
The Discover Blog -- official blog of the LAC -- has been posting useful information about how to use the 1931 census data as available now and as will be eventually. Odd detail: people on reserves were not enumerated with other Canadian residents. A separate Reserve census was taken alongside the other one. The data are available -- just not on the same pages as their non-reserve neighbours.
My family was not in Canada in 1931 (or 1941 or 1951, for that matter). But there are a bunch of 1931 people I'm looking forward to running through an Ancestry search ASAP.
Update, September 1: Helen Webberley comments from Melbourne, Australia:
My mother’s first cousins left Russia for Winnipeg in 1925 and the same time as the rest of the family came to Melbourne. Even though I am sure Winnipeg was not a major city at the time, I will look forward to learning more about their lives in 1931.
Winnipeg not a major city then? It had a population of c130,000 and growing rapidly, large industrial base, key service depot of the CPR, centre of the grain trade, gateway to the golden west....
On the other hand I see Melbourne had already exceeded a million in population by then.
