If an RP2040 doesn't fit the task because it has a pitiful amount of IO, you're now into using two anyway. Two chips, two SPI flashes, two crystals - likely more than the FPGA.
If it matters for the task, that FPGA will be able to achieve nanosecond-order IO/clock-to-clock skew times - PIO is painfully bad at this (and is executed serially.)
If the task will fit FlexIO's restrictions, the NXP IMXRT1011 at $1.70 blows away the $0.70 RP2040 in basically every metric.
