https://www.youtube.com/watch?v=dobU-b0_L1I explains that the Saleae 24MHz logic analyzer and its clones are basically a 48MHz Cypress EZ-USB chip hooked up to the USB bus and some I/O pins, but with the program loaded each time you plug it in. The 8051 doesn’t have a Flash or MRAM for its program. So you can use it, for example, in the way they have designed it, to stream parallel data over USB at its maximum sampling rate.
Sigrok comes with an open-source firmware for the Cypress FX2 chips called fx2lafw: FX2 logic analyzer firmware.
But you could also download a different program into the peripheral when you plug it in, a program to make it do anything else at all, as long as it’s plugged in. You could use it to read sensors, control GPIO pins, whatever. And these chips have a lot of pins.
(He does in fact suggest using the Cypress breakout board for exactly this.)