There is this project
https://github.com/earlephilhower/arduino-pico that implements the pico into the Arduino IDE board manager, but it still looks a little complex to me. I expec that you'd be happier with some kind of "official" project. The main attraction of the Pico to me is the fact that it can be programmed in Micropython, there have been Micropython microcontrollers before but they have been expensive or fiddly to use. The Pico also uniquely has the "Programmable I/O" (PIO) feature that should make tight timings on interfaces a bit easier too.
If I want an ARM core microcontroller to program in Arduino IDE I'd probably use one of the STM32 boards I picked up for almost nothing from China
