The Japanese official site for Xenoblade Chronicles: Definitive Edition explicitly noted that the additional features that were added to the New Nintendo 3DS port of the game will not be included in the latest Switch remaster of the game. [Thanks, @_Luxin on Twitter!]
On the site itself, there’s a notice that says that the Collection Mode that was added to the New Nintendo 3DS version of the game will not be included, nor will the amiibo features be included as well (despite the Nintendo Switch supporting amiibos via its controllers). It seems that Xenoblade Chronicles: Definitive Edition is a remaster of the Wii version by itself, though it comes with its own exclusive features like the playable Future Connected epilogue which can be played from the get-go if you want.
Back in the New Nintendo 3DS version, there was support for Shulk from the Super Smash Bros. line of amiibos, which you could tap to the New 3DS’ NFC sensor once per day to unlock a new character model or song from the soundtrack, which could then be viewed in Collection Mode. If you didn’t have a Shulk amiibo, you could instead unlock the models and songs via tokens earned via Streetpass, or Play Coins. Coins were also given out for beating the final boss for the first time, and reaching Lv 99. The Jukebox in Collection Mode could be played even in sleep mode, letting you listen to Xenoblade Chronicles tracks on the go.
Other games like Super Smash Bros. Ultimate also already support a sleep mode jukebox and playlists. That said, ultimately those were extra features meant to incentivize purchasing the New 3DS version alongside a New Nintendo 3DS.
Xenoblade Chronicles: Definitive Edition will come to the Nintendo Switch on May 29, 2020. North America’s special edition includes a massive art book, while the European one includes the art book, a soundtrack, and other goodies.