Cardfight Vanguard Dear Days is available on the Switch and PC now, and the Steam product listing shows all DLC so far. It can end up adding up. The base game is both $69.99 on both platforms. The Steam page also noted a $65.49 Additional Card Pass, as well as a number of additional add-ons.
It appears that the DLC added in the Cardfight Vanguard Dear Days Additional Card Pass is its own, separate thing. For the money, people get Additional Card Sets Vol. 1 through 4. These are [D-BT06]: Blazing Dragon Reborn, [D-LBT03]: Lyrical Monasterio: Summertime Memories, [D-BT07]: Raging Flames Against Emerald Storm, and [D-SS03]: Stride Deckset Chronojet.
As for the other add-ons, they cover card sets, character sets, and sleeves. For example, there are four $9.99 sleeve sets. Each one gives you 12 to use in-game.
Three character sets appear at $6.99 each. Each one gives you a fighter, their CPU, a deck recipe, and both standard and SD character sleeves. Aichi Sendou, Ren Suzugamori, and Toshiki Kai ones are all available.
As for the others, they are nine Rare Card Sets for $9.99 each. The cards in these can also appear in certain Rare Card Sets. Their product listings note you can buy the card sets and bundle, and it cautions about buying them more than once. There is also a warning that if you have the maximum amount of cards in-game from the set, you’ll get CP instead of the cards you bought in the DLC.
Cardfight Vanguard Dear Days is available for the Switch and PC. People playing on PCs can try it first via a Steam demo.