We've seen spren bonds, we've seen Seon bonds, we've seen Aviar bonds. We know that Cognitive Shadows can be bonded as is the case with Stormfather and
There's also a Dawnshard which is said to be able to create Bonds with mortals
Can human beings also be similarly bonded? I think yes, though we've only gotten confirmation of Cognitive Entities, including Cognitive Shadows, being bound, they only form one half of the pair, the other half is human. A Bond between two human beings should be possible, in fact, I believe we've already seen a malevolent expression of this: Hemalurgy. Stealing and grafting parts of other people's Spiritwebs. A more benign version of such a Bond should certainly be possible, akin to the Nahel Bond.
What would be the result of such a Bond? What would be the result of such a Bond if neither of the bonded have access to a magic system? If one of them is Invested? If both of them are Invested?
I think such a Bond could function akin to a telepathic link, maybe even a teleportation link as part of an Investiture system. The unInvested would also get access to the magic system of the Bondmate. If both Bondmates are Invested, I believe we might even see strange resonances. They should definitely be able to share Investiture, maybe even have an easier time converting between different types of Investiture if they have access to different systems.