We updated the behavior of boot2 so that there is now no default bootloader. Pico_explorer_showcase was the only BSP still using git:main, pin it to the last git commit before https://github.com/rp-rs/rp2040-boot2-rs/pull/7
For the HAL, currently just passes the feature to the PAC. Also pass the 'rt' feature through to the HAL for all the BSP crates.