….will allow both geared and singlespeed, drop bars, discs?

Ideally cheap too. Steel preferred, but open to anything. 100/135 QR ideally.

I was looking for something along those lines a while back; on paper it’d be the Roadrat, but that has flat bars…

Yeah.. and this is to replce my old flatbar roadrat

Aren’t pretty much all disc ready F&Fs (new ones anyway) thru axle now?

Planet X Kaffenback? Not sure if it has switchable dropouts though

Kaffenback has a fixed dropout

Surly Straggler or Bombtrack Arise come to mind.

Transition rapture

In my opinion, “pure” (tensioner-less) singlespeed is not worth the effort.

You open yourself to issues if the chainring is ever so slightly eccentric, need to re-tension as the chain stretches – the disc brake caliper needs to move with the wheel as well…
I currently use a Surly Singleator on one bike, previously used a Rohloff DH tensioner on another.

just put drops on your rat.

Unless you want it fixed or can’t abide the look of it, a tensioner does a perfect job and gives you loads more options for frames. e.g. the steel Charge Plug frames which are cheap at the moment.

Bombtrack Arise loks promising, that’s on the list

In my opinion, “pure” (tensioner-less) singlespeed is not worth the effort.

+1!
+2 if you are using disc brakes!
+3 if you are using full mudguards!