I was curious & played around a bit with EasyBCD -- a nice, free utility for working with Win10 boot menus/files, and while it won't do everything, it's Loads quicker & easier than the Windows Cli tools. If the device or system uses Legacy or CSM booting, and not UEFI, EasyBCD includes 2 interesting options, boot to Linux & boot to ISO. In both cases it adds & uses a bootmgr file as a go-between -- Windows boot loader [BCD] opens that file instead of the Windows equivalent, and that loads Linux, either installed or as a live disc ISO. It has one caveat -- normally Win10 boot files are on a hidden partition, and you have to give it a drive letter so EasyBCD can find it. Once it added the bootmgr file I removed that drive letter and it seemed to still work fine.
[EasyBCD will also save or backup your boot menu files, which I recommend regardless whatever you use it for, or if you even use it for anything else. With some of the major Win10 updates I've found that the update process added all sorts of extra entries to the boot loader & its registry, apparently based on drives connected & listed in the BIOS. They didn't show up in the boot menu, but enlarged and complicated the boot setup enough that I could tell the difference, while very slight, in boot times. I also worried that the extra complication could eventually cause problems. So I performed a backup in EasyBCD, then check the boot menu [View Settings -> Detailed] after every major Win10 update, and restore that backup if/when necessary.]
In a Win10 64-bit VirtualBox VM I tried using EasyBCD to boot the Jamulus ISO. Using the option for on disk it worked, but then stopped with an error I think related to not being able to work with the RAM disk. I tried it with the option to use a RAM disk, and it didn't work -- I *think* that maybe it couldn't find the RAM disk, and that had I added a drive letter to Win10's Recovery partition that *might* have fixed it. Or maybe it could have been RAM limitations because of VBox (?).
Next, using the same VM, I attached a .vhd file I created, formatted NTFS, and then detached in Win10. I set the Jamulus OS ISO for the VM's CD/DVD drive, booted to that, and installed the Jamulus OS to that new .vhd file [~12.6GB]. I used EasyBCD to add that .vhd to the boot menu, using the default option to seek & find the Linux OS, and it seemed to work great.
Anyway, like I said, I was just curious & playing around... I have No idea if any of that's potentially useful or even of any interest.