This is the Schrodinger by SouthPawEngineer, a board which is both wired and wireless.
Through the magic of shift registers, and some supporting circuitry, the board utilizes the Bluetooth we're all used to but has advantages over the usual split keyboard with two controllers: it is controlled by a single $10 Xiao BLE, and has the battery life advantages inherent with a unibody design – SouthPawEngineer.
The Schrodinger can be powered by a lipo battery placed underneath the top cover, or you can use 2x CR2032 coin cell batteries.
It is compatible with Gateron KS27, Choc v1, Choc v2, and MX switches.
The two halves are connected with a simple CAT5 ethernet cable.
It's also nice!view compatible.
According to the designer, because this is logically a monoblock / unibody keyboard, you'll get better battery life relative to the normal split keyboard designs that have two independent controllers and two independent batteries. On top of that, having only one controller and battery means the board on the whole is less expensive than a regular split might be.