Well, pentax wide primes are rather limited.
There is really just da 14mm f2.8, Fa 20mm f2.8 and Fa* 24mm f2
Again, this topic has been discussed quite a few times.
Da 14mm is prone to flare and unsharp corner wide open. It is not as chunky or expensive as Canon or Nikon.
Pentax Da 14mm f2.8 Images
Fa 20mm f2.8 is a tiny lens with typical Fa casing. The lens is a good performer but its PF is a troubling feature. Some copies are reported to be decentered
Fa* 24mm f2 is a fast lens but not a great performer on digital sensor. The lens has a great build with a great contrast rendering. However, its inaccurate colour reproduction and propensity to glare are rather troublesome. The corners are not sharp even stopping down to f8
Pentax Fa* 24mm f2 Images