Bring-up went well; so far, everything except one minor issue: the RP2350B's flash. Here's a picture of the board, then more about the W25Q64JVSSIQ (flash) component.

While doing the PCB layout in KiCad across 2 screens, with the mouse pointer focused on the schematic view rather than the PCB window, I accidentally hit a button, and the flash component moved within the schematic. I only realized it a few minutes later, so I couldn't use ctrl+z. I moved the flash symbol back, fixed the messed-up wiring, and continued with the PCB. What actually happened that I didn't realize is that the symbol was mirrored, and all the wiring was correctly placed, but to the wrong, mirrored pins. I then traced it like that in the PCB, and that's how my flash doesn't work in v1. Luckily, I don't need it, so I just flash to SRAM instead for this version. The flash for the iCE40 was actually untouched, so that one works! Here's a screenshot of how the mirrored symbol looked, pretty obvious, but I didn't check it in detail in the schematic anymore, as I didn't make any changes.