I found a inexpensive LCD-Viewfinder that is intended to fit Canon EOS cameras and would like to know if anyone has tried it on a K-01. The critical part of the fit appears to be the location of the tripod mount hole relative to the viewfinder. I use mostly manual prime lenses and would like to improve my ability to focus in bright sunlight. I included a link below for the LCD-V3 made in China Viewfinder.
You don't need one of those big bulky viewfinders bigger than the camera itself.
A simple diopter like the ClearViewer is all you need. Even though it's just a lens on an open hinged bracket it does actually work to see the LCD in bright sunlight because it's not the sun on the screen, but your face/shirt reflecting in it that's the problem. Unless the sun is precisely overhead, using a ClearViewer means your face is so close that it blocks/shades that reflected light anyway, like putting your face up to reflective window at night.
The K-01 having both hotshoe and tripod socket centred directly on the LCD means you can use just the standard ClearViewer straight out of the box (the specific-model ones are for when the tripod socket is off-centre so needs a made to order bracket to centre on the LCD).
I got the tripod-mount version originally for the D7000 which can fold away, either up against the LCD for storage or down and out of the away if you want to see the LCD directly. I see he makes a hotshoe version now which would make it even easier to attach/remove as needed, in which case I probably would have gotten that one myself instead I think.