Nintendo of America replied to our question regarding availability of the accessories featured in this article, simply saying "we have nothing to announce on this topic." If Nintendo should announce availability for these at a later update, we'll make a new post.
These include a colourful Pro controller with a fetching Splatoon 2 design as well as a case, both coming on 21st July along with the game. There will also be a neon red/blue Switch bundle which includes a copy of Splatoon 2. No information has been given yet regarding pricing.
Nintendo also announced a neon green and pink joy con set, which will be available sometime this Autumn. There's no word yet on whether or not these will be available in North America. We've reached out to Nintendo of America and will update this story once we receive word.