I'm using miryoku on my kyria, but because I wanted to customize encoders and other things I just made the layout like miryoku my self (in a qmk config), and added the tweaks I wanted.
I remember looking at the miryoku repo and not seeing a way to compile the firmware from there and also customize it easily.
Yes this will be the step 1 - right now I am not able to flash the default, that's most likely because I am completely new to qmk... Will put extra time in soon.
cheapino is using the split_3x5_3 layout that Miryoku QMK already supports, but cheapino doesn't have community layout support enabled, so it won't be used. If /u/Tompi@discuss.tchncs.de fixes that you'll be able to build by merging branches and building for cheepino. You can merge the cheepino branch automatically at build time by using tompi/qmk_firmware/cheapino with the Miryoku QMK build workflow branches option.