Adding to the Northern European airlines to Canada with WestJet interline list is
Finnair's announcement that they'll return to YYZ in Summer 2026.
According to EF, AY and WS already have an interline agreement, which I assume is a holdover from when AY last served Canada in 2015? Either way, while I imagine the SK relationship will be fairly involved, I assume AY will do the oneworld (except QF) standard of selling WS-coded Economy-only connecting flights to YYZ for feed.