Hey Sanny, I’ve done odd bits of Kungsleden on bike foot and ski, as well as some bits around it, but thats closer to 400km so not sure its the same thing you’re on about (kungsleden = King’s path).
Assuming it is, then it’s perfectly doable in summer. I’m sure I’ve read a couple of blogs or forum posts about people attempting it in a ‘race’ style, similar to a whw double. Plenty of info and posts available on swedish sites for trip reports etc. YouTube also has some vids around some of the popular bits, where some classic rides also use bits of the route iirc. There’s also at least one book on riding the whole route.
Edit- see you’ve posted on happymtb already. I’m sure a search on there will also drag up old threads and the reports I forget above. If you need a hand translating any bits and pieces later, post them up.
Also see that the chef has posted a link to the book I was thinking of. No idea how good it is, but worth a look.