A custom PCB by bigbrobewatching (pics). What's more interesting though, is the workflow: KLE, KLE PCB generator I wasn't aware of & the firmware builder by Ruiqi Mao.
KBD.news Published February 27, 2021
Hey, it seems there' not much content here.
That's not surprising because kbd.news was a mere link collection for about the first six months.
Another formatting of the old lead may reveal some links:
There are two completely different keyboard matrices referred to as duplex matrix. Let's examine the Japanese one, which makes possible to handle 160-200 keys with a single Pro Micro.