Would be neat to see the Chinese communists represented, they should have special guerrilla abilities (may be placed in an occupied territory, attacks on a 3 for the first round). They should also get an IPC bonus (maybe 3-4) if nearby Russia maintains nearby territories. Goes without saying they can’t occupy the same territories as Nationalist units.
Canada is definitely a no-brainer, I would let them start with what’s on the board and just add a destroyer at SZ1, and they get a 5 IPC bonus if they control all their original territories plus Newfoundland/Labrador.