If you want P-TTL radio-controlled flash gear, I'd recommend Godox.
The X2T-P, Xpro-P, or Flashpoint R2 Pro II transmitter can do TTL/HSS with Pentax gear.
And Godox speedlights have built-in 2.4 GHz transceivers that you can use with those transmitters. The only on-camera TTL speedlights for Pentax are the US$85 TT350-P and $260 V1-P. The TT600 ($60) and V850II ($140) are single-pin manual flashes (but like the YN-560 gear, you have M power/group control, and unlike the YN-560 gear, you'll also have HSS). And if you only plan on using this speedlight off-camera for studio-type lighting setups, all the "flavors" of the Godox V860II ($180) and the Canon version of the TT685 (TT685-C, $110) can be firmware updated to be P-TTL radio slaves (but their feet will still be compatible only with the brand it's dedicated to).
TTL gear can always be put into manual mode. But manual gear can never do TTL.
And the two Pro transmitters can both do Godox's TCM (TTL Convert to Manual), so you can use TTL to set the initial power level, instead of having to meter or guesstimate/shoot/check/adjust/reshoot, and after it's set where you want, you can lock the setting into M, so you don't have shot-to-shot variance.
The Strobist recommends the TT600 and an X2T or X1T transmitter, but I think TTL is always nice to have.
In addition to this,
the Godox system includes larger than speedlight options, so if you really get into lighting, expanding up to studio strobes is something you can do with Godox; not so much with Yongnuo.
See also:
The Godox XPro-P flash trigger is a "game changer" for Pentax photographers - DIY Photography