The Pico Indicator is a simple board with 29 LED for use with Pico, Pico W, Pico 2, Pico 2 W and compatible boards to show which pins are logic level high.
There are 3 RED LED for power (VBUS, VSYS, 3V3) and 26 AMBER LED for GP0 to GP28 (excludes GP23, GP24, GP25 which aren't exposed on the Pico).
Each LED is aligned with the pin, the GP number (or power name) is printed along side it on the board. The LED is then connected via a current limiting resistor and a solder jumper before going to the pin. If an indicator interferes with the signal (when reading an ADC for example) the solder jumper on the underside of the PCB can be cut isolating it from the GPIO pin.