Here’s a GT with a typical FIRE setup for 2H guns.
It’s taken from this build.
You can basically use this for any 2H fire purifier - no matter what gear exactly you’re wearing. I also leveled by building up this devotion map. Worked fine. Fire “staples” are Solael’s witchblade, Magi, Ulzuin’s torch. Kraken is almost mandatory for any 2H build. Apart from that, you can switch devotions in and out.