NPM Package - Svelte 5 component

Hi all,
I wanted to create an NPM package with a single, simple, component written in svelte 5 (using runes and props).

I've never created or published a package before, so I searched online and found:
How to make a svelte library / a custom svelte component npm module? : r/sveltejs

Unfortunately I couldn't make it work: I get a bunch of errors, and each time I try to solve them a new one appear. Last one was: "... 'package.json' needs an import attribute of type "json"". Can't seem to find anything on svelte's docs as well.

Do you have any link to a good tutorial/example repository I can take a look at?
Thank you in advance!