From
this article, there are 21, with John Gilmour on the taxi squad for Canada, and Spencer Foo likely for China though their roster has not been announced yet.
Canada
Adam Cracknell
Corban Knight
Ben Street
Tyler Wotherspoon
John Gilmour (taxi squad)
US
Kenny Agostino
Nick Shore
Finland
Markus Granlund
Sweden
Joakim Nordstrom
Oscar Fantenberg
ROC
Pavel Karnauhkhov
Nikita Nesterov
Alexander Yelesin
Germany
Tobias Rieder
David Wolf
Switzerland
Raphael Diaz
Reto Berra
Slovakia
Milos Roman
Marek Hrivik
Czechia
Michael Frolik
Roman Cervenka
China
Spencer Foo (unofficial)