So I have Raspberry Pi OS on a microSD and RecalBox on a USB thumb drive. The boot order is SD then USB. So to get into RecalBox I have to shut down the Pi, remove the microSD card, then turn it back on (which I don't like doing because aside from being annoying, I don't want to misplace the tiny microSD card or put unnecessary stress on the case every time I do this). Both of these OSes are already installed and configured and I would rather not mess with them directly, so is there a way to either
a) just have it ask me which device to boot from every time I turn the Pi on, or
b) hit some key while it's powering on to let me choose to boot from the USB stick even if the microSD is still inserted, BEFORE Raspberry Pi OS itself starts booting? I tried mashing some of the keys that would normally do that on other computers and I couldn't find any that work (it does boot very quickly though so maybe I didn't try the right one or mistimed it or something), or
c) do something within Raspberry Pi OS that will tell it to reboot and boot from USB just once (so like, I shut down Raspberry Pi OS and it boots into RecalBox just once, but then when I shut down from RecalBox it goes back to booting from the microSD card?)
