Opened up a random microsoft keypad. It has no names on it, which I hate.
but if you open the battery compartment, which requires a screwdriver, there's a label in here. Model 1558, FCC ID C3K1558.
opening the back, it's got one little PCB, and that's all.
The membrane to the front is held on with ultrasonic welding
The PCB is pretty simple. It's got a built in antanna, a couple mosfets, and two chips.
u2 is a 6-pin chip with the label "RAR" on it. Probably something voltage related, given the position.

The main chip is an nRF24LE1 from Nordic Semiconductor.
It's a microcontroller with 16 kilobytes of flash, 1 kilobyte of RAM, another 1.5 kilobytes of NVRAM, and it does 2.4 GHz wireless.

AND PUNCH OUT ANOTHER ENTRY ON YOUR CARD, IT'S AN 8051!

@foone I've been trying to escape 8051 since like 1993 and it still keeps popping up! Come on RISC-V, save us!
@todbot @foone RISC-V emulator made out of entirely 8051!
@fozztexx @todbot @foone Hush, don't give WCH ideas. What they've been doing with 8051s recently defies belief.
(They are also ARM and RISC-V licensees too)