The 2040's PIO is indeed similar but the PRU has features the PIO doesn't like IOs directly wired to CPU register bits so the result of an instruction is immedi

The 2040's PIO is indeed similar but the PRU has features the PIO doesn't like IOs directly wired to CPU register bits so the result of an instruction is immediately available on IO lines. edit: also Ti's PRU has been around waaaay longer than the RP2040 so the PRU is likely an inspiration for the PIO.