this is a question to the experts...
I have two images (.img) of linux distributions with boot and data partition for a handheld device. Now i'd like to combine both distributions to have them on ONE image with a dual boot option. Is this possible?
Yeah, probably... There's some ifs and buts with how the .img files were made, and we'd need more details for that.
You'd first need to start with partitioning from a live USB or optical media. You'd then expand the .img files, one into each partition. If you need to, you'd have to have a UEFI partition. You'll need a minimum of two partitions, though maybe 3 - all with the appropriate flags.
Either way, you'd then boot into a live USB, picking one of them to chroot and install GRUB. That should use the os-prober functionality to find both OSes. If it doesn't, you'd have to edit GRUB manually. With enough work, you should be able to make it function.
There are almost certainly easier ways to go about this. Extract the data you want to keep from the .img files, do a clean installation, and import that data. Really, consider that idea.
Unfortunatel Ventoy doesn't work Is it for PC only?
I have a RG351 and like to use two linux distributions on it.
One is Ubuntu 19.10 the other one is Emuelec. I created a micro sdcard with Ventoy and put both images on it, but it doesn't boot like that.