Pokémon Video Game Championship Series events will begin the season using the 2019 Ultra Series Format on the Pokémon Ultra Sun and Pokémon Ultra Moon games on systems in the Nintendo 3DS family. Events will transition to Pokémon Sword and Pokémon Shield on the Nintendo Switch system beginning on January 4, 2020.
The full breakdown of the season's Video Game Championship Points structure can be found here.
I found that here: https://www.pokemon.com/us/play-pokemon/pokemon-events/pokemon-tournaments/
This tweet says it will be Sworld and Shield.
Maybe but chances are no they advertise entering worlds by winning rank battles in S&S.
Edit:you can use us/um to get closer to the sh/sw championships until 2020. So basically until championship year you can.