I finally got One Pace set up on jellyfin! I'm embarressed to tell you how long it took to figure out how.. If youre interested in how let me know.
EDIT:
omg i didnt realise so many people would want to do the same lol
i used this:
https://github.com/luucaslfs/one-pace-for-jellyfin
it gives a good guide on how to set it up and what formatting to use, but be prepared to use a terminal.
Also another heads up, not everything snapped right into place. i had to change the metadata for each arc for example set romance dawn as season 1, orange town season 2, syrup village season 3 ect as well as change the title names to the arc names.
i also had to find my own one pace series poster aswell.
i would say this mostly worked after that, but whiskey peak and arabasta didnt have any metadata at all, so again i had to do that myself. but id take that over doing everything myself. Hopefully the full thing works for you guys though. Let me know.
i also found this link:
https://github.com/SpykerNZ/one-pace-for-plex
i was going to use this as an alternative if this didnt work as i read someone got it to work for jellyfin. so if you need a back up, you could give that a try.
I hope that helped.