"Even if Canada and Australia don't join the EU as full members"

The European project is bigger than the EU - that's just the central core.

There's also the EFTA, EEA, CEFTA, CU, Eurozone, Shengen, CoE, and Swiss-style bilateral treaties.

See https://thisbugslife.com/2021/05/10/graphic-representation-o...

Canada can easily find a home one of these.