Kokko, 19, spent the majority of the 2022-23 season with Hermes of the Mestis league, the second-highest men's professional league in Finland. He posted a 4-6-4 record with a 2.95 goals-against average and a .901 save percentage. The netminder appeared in three playoff games for Hermes, finishing the postseason with a 1-2-0 record, 2.31 goals-against average and a .917 save percentage. Kokko also played in eight regular-season games for SaiPa of the Liiga league, the top men's professional league in Finland. In those games, he had a 2-2-1 record with a 2.98 goals-against average and a .903 save percentage.