As John explained, it's 100% doable. The feather board we used contains an Arm Cortex M0 and the Pi Pico contains an Arm Cortex-M0+. Both can run micro python and both can be used with the Arduino IDE.
That said, I'm not aware of anyone using a Pico to interface a 3rd party anemometer with a Davis ISS.
We've actually retired this project. We have two coastal stations that we'll continue to use our adapter on for now. The rest of our stations we've switched to the stock Davis anemometer. We did the math and discovered it's cheaper to just use the Davis anemometer in the long run. We plan on replacing speed cartridges yearly and the entire anemometer every 3-4 years.