At the end of today's Crown Tundra stream, Pokémon Company President Tsunekazu Ishihara confirmed that players will be able to transfer Pokémon from Go to Home later this year. This will enable creatures that you have found out on your travels to then be transferred over to Pokémon Sword and Shield.
It was also revealed that players who transfer Pokémon from Home to Sword and Shield will receive a special Melmetal that is capable of Gigantamaxing. This is massively useful, as before the way to obtain Melmetal was to open a special item called the Mystery Box and obtain a whopping 400 Meltan candies.
Players should remember though that to be able to successfully transfer Pokémon from Go to Sword and Shield the Pokémon need to be within the Galar Pokédex.