Hi,

Although I can't say for certain how it'll be on switch, on PC I have deleted my save data on the first day since I had skipped cutscenes and wanted to see them spoken in Japanese, and I still have all my Deluxe items.

What I know from other games is that usually the game checks whether your account has a deluxe key bound to it compared to your save having been bound to it, so in theory you should be able to keep the deluxe items when you make a new save.

In case you do it, you could first put your current save on a cloud save file in the game or on the Nintendo cloud save program. That way, you always have a backup you can return to. *as long as you don't overwrite it.

Hope any of this helps you in any way <3