i don’t know if this is available with the stock keyboard bios but if you upgrade it to Custom PicoCalc BIOS/keyboard firmware, you can reboot by holding shift and tapping the power button (although, to return to the UF2 bootloader i have to power cycle since i need to hold F1 from a cold boot for that to come up instead of the last firmware flashed)
i also recommend you replace the stock bootloader with UF2 Loader release as this will allow you to use standard UF2 images rather than BIN files that need to be specially compiled