That would be nice to have folder structure for studies. Lets say I have various studies about sicillian opening. I want to put them in single folder. Or similarly I have studies about pawn endgames, I would put all my pawn ending studies in single folder. Everyting will be more organized.
have you tried using tags? they fulfil the same purpose, and are in fact superior because a single study can have multiple tags. for example, here are all studies with the lichess4545 tag: https://lichess.org/study/topic/Lichess4545.com/hot
and here are all studies created by "me": https://lichess.org/study/topic/Lichess4545.com/mine