Omori is a game about escapism because Sunny has to avoid all his friends and dealing with the truth of his actions to explore more of Headspace. Headspace is a hugbox that stagnates Sunny and he only grows from real world interactions. Headspace is just a distraction.
Deltarune isnt even about escapism because Kris must confront his bully and interact with people he's been avoiding to progress in Dark Worlds. In Dark Worlds Kris furthers his real world relationships and confronts his own flaws. Dark Worlds are not an escape, theyre a fundamentally real thing and it's Kris's duty to close the fountains for the safety of the real world.
Playing piano alone or whatever Kris was doing before chapter 1 was actual escapism.