The shopkeeper's name is Nesta. She is a humanoid Anglerfish and is secretly Myles Sister but can't tell him because if CHASE finds out she will be targeted. She looks like this in the scratch realm because this is the sprite she took as a host. She gives Myles info on the monsters and gives him items and perks, at a cost of some bits. The keys help her escape as well.
Definitive shop for now. Any questions ask me.