Nice.

I wonder if 264/520 kB RAM is also enough for a high quality parametric stereo reverb/echo effect? Should fit about 3/6 seconds of uncompressed 16-bit 44.1/48 kHz audio.

Also: Raspberry Pi Ltd - please keep increasing the RAM size in future iterations to unlock even more use cases.

The RP2350 (Pico 2) supports external PSRAM so you can add several MB more there if you need it.