Hardware Acceleration on DS218+

[Efficient_Good_5784]

1) JELLYFIN_PublishedServerUrl=192.168.1. # is this a placeholder and should I add the IP my NAS owns? And as there is a # at the beginning, isn't this entire line just a comment?

If you don't need it, you can just leave it as a comment (or delete it). It's not required to use Jellyfin.

2)
PUID and PGID should be 0,or should I look for my personal IDs?

If you delete both PUID & PGID, or set them both to 0, your Jellyfin container will run as root, which means it will have access to everything on the NAS. If you don't want that, you'll need to add the user and group ID of the user that you want to run Jellyfin with. Just make sure your media and folders meant for Jellyfin are accesible by the user.