The easiest way to answer the question “What is dreampunk?” is to throw out some good examples of the genre and let you see for yourself. Some of these (like The Sandman) feature a dreampunk premise and exemplify the genre the whole way through. Others (like Adventure Time) vary by episode in their degree of dreampunkiness. This list is by no means complete, so please add your own examples in the comments.
The Sandman (2022–)
Severance (2022–)
Nine Perfect Strangers (2021–)
Stranger Things (2016–)
Adventure Time (2010–)
Including Distant Lands, and Fionna and Cake.
The Last Days of Ptolemy Grey (2022)
Moon Knight (2022)
Undone (2019–2022)
Russian Doll (2019–2022)
Westworld (2016–2022)
Behind Her Eyes (2021)
WandaVision (2021)
The Midnight Gospel (2020)
Dispatches from Elsewhere (2020)
The Good Place (2016–2020)
Dream Corp LLC (2016–2020)
The Feed (2019)
Lodge 49 (2018–2019)
Legion (2017–2019)
The Good Place (2016–2019)
Mr. Robot (2015–2019)
Maniac (2018)
Twin Peaks (1990–2017)
Including Fire Walk with Me and The Return (a.k.a. season 3).
Someone else I interviewed on my channel did a long in-depth analysis on Twin Peaks, I think you will like it:
https://www.youtube.com/playlist?list=PL7bsYHsRUfm4fs6WJXvULkgCt8JQJrjL-
Great list. There's a few here I need to see. Would love for you to watch The OA on Netflix and hear your thoughts!