There’s a collection of over 535,100 publications, including more than 414,300 digital publications available from Government of Canada Publications.
Most published prior to the 1990s are in digital form. Since 2000 most documents have been born digital.
What’s of interest? It’s a real mixed bag, and there’s a catalogue to help find what you need. You may well find things you didn’t know you wanted, especially in the older items.
Organizations, such as Statistics Canada digitized historical documents, in Statscan’s case summaries of census findings back to 1851-52.
The Statistical Yearbook of Canada 1890-1905
Sessional papers of the Dominion of Canada 1868-1925.
Directories of Marine Scientists in Canada during the 1980s
Give it a try.