Thanks Longpanda for Ventoy!!

[spanspek]

You can convert .sblive to ISO file by systemback and boot the ISO file by Ventoy.

Yes, thank you, however the 4GB limit of systemback iso creator prevents me from doing exactly what my plan is.

If adding .sblive support is difficult or cumbersome I will understand.

I do have a workaround to create those larger images ...

sudo tar -xavf /home/systemback_live_2020-11-15_1.sblive -C sblive/
sudo chmod 777 -R sblive/
mv sblive/syslinux/syslinux.cfg sblive/syslinux/isolinux.cfg
mv sblive/syslinux/ sblive/isolinux/
xorriso -as mkisofs -V sblive -J -l -b -isohybrid-mbr sblive/isolinux/ -c isolinux/boot.cat -b isolinux/isolinux.bin -iso-level 3 -no-emul-boot -boot-load-size 4 -boot-info-table -eltorito-alt-boot -e boot/grub/efi.img -no-emul-boot -isohybrid-gpt-basdat -o sblive.iso sblive

Thanks for your response anyway, and of course for Ventoy!! Could you please tell me about the origin of the name "Ventoy"?