Anything not labeled ‘3PP’ and that fits the campaign setting that you can find on d20pfsrd.com or Archives of Nethys is legal for play, subject to GM approval.
For equipment, anything not marked with the Crossroads icon of Pathfinder Society on Archives of Nethys is not legal for play. Basically, equipment on the banlist for PFS is also on the banlist here.
This dungeon is pretty nasty, so feel free to go crazy. If you enjoy it – play it. As long as you’re not taking away from another player’s enjoyment or stealing the spotlight.