While they offer digital downloads on the eShop, their pricing actively discourages it.
Case in point: I just bought my kid a new first-party Switch game. Physical copy on Amazon was ~25% cheaper than the identical digital version on Nintendo's own eShop. Even my 9-year-old noted how illogical it seems, the physical version requires manufacturing, shipping, retail markup, yet costs significantly less than the digital bits that have near-zero marginal cost.
It strongly suggests Nintendo wants the physical retail channel to thrive, or values the perceived permanence/resale value of cartridges.
This context makes the Switch 2 "gamekey" cartridges (physical auth token, digital download) fit their pattern of valuing a physical artifact and retail presence, even if the data delivery shifts.