Sounds awesome,
I have had similar plans for northern Scandinavia that never left the drawing board (but not in the pile of lost dreams either :)).
I would absolutely go for packrafts and two boats. Using two boats will in my opinion add alto of safety. If one totally breaks down or is lost with combined injury, you can take what is absolutely necessary and continue to safety in one boat and on land, or in worst case leave injured person in a camp and head for help in the remaining boat.
Two boats in the water also means you can give some rescue if one flips, lose his paddle down the stream etc.
I’m quite small and should have taken a single packraft but in greater size for squeezing two persons in if it comes to that and have more room/buoyancy for equipment.
I would only consider kayaks or canoe for flat water were you expect alot of paddling on flat water.
If so, these boats are a bit of a classic choice here in the north https://www.bergans.com/catalog/gear/ally-canoe/allround? , look at the videos of Norwegian adventurer Lars Monsen for inspiration and what the canoe can handle. (He did however go over to packrafts on some of his later hikes and seemed very pleased with them)
/G
