Government procurement takes a lot of time to see through to completion; Palantir is not a new company, they're over 20 years old now. To succeed you also need money for lobbyists; regardless of what you feel of them they are a necessary part of the system. Also at the government level, especially at the level of federal governments, you are competing with Oracle, IBM, and other similarly large companies which is difficult to do if you are a new, small company.
Lack of investment probably. No one is investing in Canadian companies. A stupid amount of Canadian investment is in America or overseas, very little is domestic
Canada should make some rules to fix the lack of investment. If Canadians were not allowed to invest in American companies the problem would be solved.