Do you even know what the Confederations Cup is? It's a trial World Cup, with all of the continental championship winners, the current World Cup Champion and the host nation. So the level is much higher than just picking some random teams you did, as the asian and african teams in soccer actually are decent teams.
I would be interested to see how you'd make an argument of just having U23 players (+3 older) here in hockey and get the level to be massively, hugely improved and how that would stick as a correct statement. I guess this is what happens when the WJC is so overrated. Because it surely would make the level only worse.
The U23 teams would have Conor McDavid, Nathan MacKinnon, Mikko Rantanen, Alex Barkov, Jack Eichel, David Pastrnak, Auston Mathews.
Without question I think the USA and Canadian teams would be much better. The issue for the smaller hockey countries would be depth. Germany would probably be pretty bad after Leon Draistl. The Czechs would have very limited depth after Pastrnak. Both those teams are semi finalists as constructed now.