Booting from SD card

I see conflicting info here and on reddit. A few questions:

  1. Will a Librem 13v4 boot from an SD card?

  2. If I have multiple SD cards with different OS’s and boot partitions, will that render PureBoot useless? Or can I store multiple profiles, one for each SD card install? If I don’t use Heads, would swapping SD card installs around create any problems for Coreboot/SeaBIOS?

  3. To confirm- new 13v4’s come with Coreboot + SeaBIOS, but not Heads, right?

Thanks!

Found a partial answer. The FAQs confirm that with coreboot, you can dual boot from the SD card.

So I guess my remaining question is how Heads and the Librem Key work if you swap cards with different operating systems installed on them. What I ultimately want is just to know that the bios hasn’t been altered. I could live with not knowing if the boot partition had been altered. Is that doable in this scenario?