Juniper Hills is a fictional mental hospital based on the real life Dorothea Dix Psychiatric Center in Bangor, Maine which opened in 1896. Many of King's novels include Juniper Hills including It (2017), which is where Henry Bowers was locked up after the 1958 incident in the sewers when his hair turned white.
Odin Branch hearing voices telling him how to build something could be a reference to Tommyknockers, another novel by Stephen King.
Ruth spilling pills onto the floor and seeing The Kid walk into the house is a possible reference to a scene in It (2017) where Eddie drops pills onto the ground and sees Pennywise. Both The Kid and Pennywise are played by Bill Skarsgård.