The K24/2.8 is surprisingly good for f8-f11 work.
I had mine adjusted to focus a bit past infinity to get the edges to be better and after that, no complaints for me on IQ esp when considering the size of the lens (ie. not big)
I did not like the f1.8 Sigma 28 and 24mm (and for that matter the FA*24), they all seemed to be catered for fast aperture nearer focus distance work, giving good isolation and low light ability, but for infinity focused f8-f11 stuff, the off center was not that sharp imo.
Probably field curvature and the combination of the thick filter stack of the un-modded A7 I tried all 3 lenses on; So it may differ on the K1.
For the K24/2.8, put it this way.
At first, I was not satisfied with it on the K1 and was planning to get a Zeiss 25/2.5, but once I resolved the issues with the focus adjustment, I gave up the idea.