I don't actually do full conversion requests (just a little too busy for that) but I can certainly help you get started. I've never done a card with Affinity for Artifacts, but since the Tooth and Scale are items, I'd probably stat them as requiring attunement, but not "counting" towards your attuned items in some way. That way you can balance them around being used by only 1 party member at a time, but without limiting their use.
As for what they are, the Tooth and Scale should totally be a weapon and shield. I'd say make them each function as a +1 sword and +1 shield, respectively, but with a twist since they've coming from a dragon. Something like the tooth ignores resistance to slashing/piercing damage, and the shield also provides resistance to fire damage?
Chiss-Goria itself is a lot more complicated. By my usual conversion formula, it would be CR 30, which is *huge*. I don't usually recommend doing this, but for Chiss-Goria's affinity for artifacts, I'd maybe flip the usual script and do something like give it resistance to damage from magical weapon attacks, instead of the usual resistance to nonmagical damage. Its also got hexgold plating on its body (a type of material featured in the recent All Will Be One stories for MtG) that I think should give it both the Magic Resistance trait, but maybe also the Reflective Carapace trait from 5e's tarrasque. Other than that though, just a big dragon (preferably one with an extra-strong fire breath!)
