Always is a strong word in this context. There are a lot of inconsistencies with world and dungeon drops. I can be in the same dungeon and have an item drop one level one time, then another level another time.
But from my experience, Gnomer is probably the best place to get ilvl 28 blue armor. Weapons don’t scale to ilvl, they scale to 30 so can’t be used on a 20. And Dungeon specific drops don’t scale either down to 20.
Not sure Keller’s is available in Gnomer, but u can get some juicy blues in there, but like world farming, it’s still hard going and low drop rates.
Good luck
I still like to pop into Gnomer from time to time to see if I can get lucky.