Pokémon Home links to Pokémon Bank to allow you to carry forward stored creatures into current games. While a free version exists, players who are serious about bringing their Pocket Monsters forward are probably going to want to look at the $15.99/year (or $2.99/month if you just want to do this once) Premium plan, which bumps your storage capacity up from 30 Pokémon to 6,000, as well as higher capacity in Wonder Box and GTS.
In addition, just for downloading the app and linking it to your Nintendo Account, you get a free Pikachu, as well as your choice of one of the Kanto starters (Bulbasaur, Charmander, or Squirtle). In addition, Serebii reports 35 Pokémon previously not available in Sword & Shield are available if you transfer from an older game using Pokémon Bank. You can see the full list here.
Pokémon Home is available now for Switch, iOS, and Android.