You don't have to find anything. You're entitled to your opinion but plenty of people including versed music critics' agree with my take. Cheerio

It's not about psychedelic or whatever you're referring to when you say prog.

Originally, prog meant incorporating jazz elements into pop. If we use that definition, most prog rock from the 70s isn't prog.

Honestly the bottom line is lankum take the framework of folk and use other genres peppered in to create an expansive experimental folk sound. Whether you like it or not, this is the core definition of prog and always was. If you care enough, you can DM your prog heroes and show them this description.

Actually the real bottom line is: trying to label genres and subgenres into an experimental sound is futile and constrictive and pretty fucking pointless imo rendering this whole thread redundant.

Clearly you don't know your prog. Prog started as prog-pop born out of psychedelic bands trying to incorporate other less mainstream genres into pop music.

Prog Rock as you probably know and love is the second wave of prog.

Rush and King Crimson etc don't own the word prog.

Lankum absolutely fit the prog-folk label as they maintain folk roots but add in drone and other niche styles to create something more expansive and layered.