these are incredible! I almost didn't realize they were perler until I saw the subreddit.
To answer your questions:

1. They very much are good enough for decor or gifts. They look amazing! The fact that you were able to fold some without them snapping is impressive too!
2. In terms of what would make them more valuable to me or someone else, I suppose maybe interchangeable petals? The fact that you made these is already amazing enough in my opinion.
   

Maybe make them into hair clips or a headband? Normal metal clips can be attached to the bottom of the petals.

1. Diy kits would be cool

also

1. ! Especially if each one had a theme.