First warning, I drive spikes through people who repeatedly insist that Reckoners is cosmere.
If it wasn't set on earth it would be a pretty awesome cosmere novel but I think it's be too relevant to the entirety of the cosmere, it would've needed to be released later in time for it to work as a cosmere novel, otherwise we've got multiverses already with Shards or Splints that can cross into other multiverses and influence things which makes for a big ball of confusingness.