All the popular radio TTL flash triggers, like PocketWizard or RadioPopper, seem to be only available in Nikon and Canon flavors. Are there any models capable of transmitting Pentax P-TTL data?
This radio trigger appears to support P-TTL and high-speed sync.
I found this in this dpreview forum thread: http://forums.dpreview.com/forums/readflat.asp?forum=1036&message=40799541&changemode=1
The following radio-based flash triggering systems can communicate TTL for Pentax:
The Cactus X-TTL system with their V6II/IIs triggers can give you remote power control over TTL Pentax flashes, HSS sympathy triggering, and full TTL passthrough to an on-camera flash mounted on top of the trigger, as well as P-TTL with remote flashes.
Phottix's Odin II triggers.
Godox has XPro-P and X2T-P transmitters that offer P-TTL and HSS compatibility with the Godox X system. At this time (Nov 2019) however, the AD360II cannot be used in P-TTL/HSS off-camera, and the TT685C is the only TT685 model that can be firmware upgraded for off-camera P-TTL. The only P-TTL speedlights in the Godox lineup are the TT350-P and V1-P.
The Aokatec AK-TTL works something like a poor man's RadioPopper—it takes the light signals used by Pentax's wireless flash system and turns them into radio signals then translates back out the other end.
The Acon R930 seems to be using the hotshoe protocol to communicate TTL, since it uses all the pins/contacts on the flash hotshoe, but bridged over radio, but doesn't look widely available.
The Conanmark ABC TTL radio triggers have a Pentax version, but it doesn't look like it's widely available.