Wii U eShop titles are linked to the console, not to the user's account. Ignoring the fact that the Switch runs on completely different hardware, you can't even

Wii U eShop titles are linked to the console, not to the user's account. Ignoring the fact that the Switch runs on completely different hardware, you can't even transfer your purchases games to a new console if yours breaks. Your only option is to ask Nintendo nicely to link them to your new console and hope they will.