You can get the official standard Pico board for 4€/$. It is not worth the trouble to order a cheap malfunctioning clone from China.
The reference for Ada on RP2040 is Jeremy’s page Ada on the Raspberry Pi Pico.
You can already do quite a lot with the light runtime (ex-zero-footprint). I also had good results with the light_tasking runtime. See GitHub - damaki/rp-runtimes: Ada/SPARK runtimes for the Raspberry Pi RP2040 and RP2350 and the discussions here and here