Richard Goulter aka rgoulter/richardgoulter shared two of his ortholinear keyboards built around the cheap CH552 MCU: the CH552-48 with on-board controller, and the CH552-44 with a daughterboard and handwiring in mind.
A very simple 48-key PCB which uses the CH552 MCU. […] The CH552 is cheaper than the RP2040, although is less powerful – richardgoulter.
CH552-44 specs:
44 keys, ortholinear (4x12-4)
MX
hand solderable
WeAct Studio's CH552 devboard
BM40/JJ40-compatible (same mounting holes)
CH552-44
CH552-48 specs:
48 keys, ortholinear (4x12)
MX
on-board CH552
BM40/JJ40-compatible (same mounting holes)
CH552-48
The keyboards use semickolon's fak firmware, which uses the sophisticated and modern Nickel configuration language to declare keyboard and keymap definitions.
Since the CH552, although cheaper than the RP2040, is much less powerful. you're probably not going to get Vial on a CH552 keyboard. In practice, fak seems well suited for small-keyboard enthusiasts.
A couple of examples of keymaps declared using Nickel are available here and here
The BOM & CPL files are included in the release; which means if using PCBA (e.g. from JLCPCB), the only soldering required would be the keyswitches.
Resources:
Kicad source files, gerbers, firmware, files for lasercutting plates etc. available here: