05-28-2021, 05:50 AM
I'm not sure what happens if an update to an OS on the multiboot SD image installs a new kernel or bootloader version. The tool that generates the multiboot image is public, so you should be able to use it yourself to generate an SD image with more up to date OS versions.
https://megous.com/git/pinephone-multi-boot/
https://megous.com/git/pinephone-multi-boot/