I really need to be able to do at least one of two things:
Convert an ISO file which is in the ISO9660 format to an ISO that uses the EXT4 format.
Transform a bootable drive which is in EXT4 into an ISO of the EXT4 file system.
It can't be ISO9660 because correct me if I'm wrong, but as I understand it, ISO9660 is only for CDs/DVDs, but I want to use a USB stick. I created these files using Linux Live Kit (it gives me an ISO9660 file and a ZIP file which can be made into a bootable drive, which I used on an EXT4 drive). I can boot the drive (though only in Legacy/CSM mode for some reason, but I'd prefer UEFI - can I do that?), but what I really need to do is boot this using Ventoy, which requires an ISO, and it seems that ISO9660 gives it an error such that it can't recognize the file system. Hence the reason why I'm trying to make an ISO with EXT4 from the data on the EXT4 bootable drive.
I've tried doing so using dd and Disks, but it makes a 4.3 GB file and then says there's not enough space, even though the drive that I'm saving it onto will hold many additional GB, so I think (but I'm not certain) that it's complaining that it can't be more than 4.3 GB because that's the max size of a DVD (but I don't see why it turns out that big, anyway, because even though the installation is more than 7 GB, the ISO9660 and the ZIP file are both like 1.5 GB).
So, what am I doing wrong?