Seems like third party titles are offering upgrade paths for Switch 1 games for their equivalent Switch 2 ports.
https://tech.yahoo.com/gaming/articles/hogwarts-legacy-civilization-7-more-190135112.html
Hogwarts Legacy, Civ 7, Rune Factory. Hogwards Legacy was interesting, as I did not see that happening going by its reveal.
Note that Nintendo charges for some upgrades and additional content.
https://www.nintendolife.com/news/2025/04/nintendo-confirms-upgrade-pack-price-for-more-switch-2-edition-titles
But they also offer free upgrades to select titles:
https://www.nintendo.com/en-gb/Hardware/Nintendo-Switch-2/Nintendo-Switch-2-Free-game-updates-2786093.html







