This is how I boot Puppies in ISO move inside Windows hardrive Frugal
This example is for fossapup64 but it works for others. I use a third party bootloader called EasyBCD (the free community support): https://neosmart.net/EasyBCD/
I just put the .iso in the root of any partition and rename the iso to anything...in my example I renamed Fossapup64 to "puppyy" that was a name I was experimenting with and I never changed it and left it as is...This also gives me the ability to just rename any puppy derivative as "puppyy.iso" with out adding a different boot entry...
I used dvdfab virtual cd drive to extract the sfs files from the iso. DVDFab is a reputable company that has been around for many years: https://www.dvdfab.cn/virtual-drive.htm
The two images above are videos^ If the website doesn't play it automatically, put .mp4 at the end of the link.
This is how it looks when I boot up (I deleted the other same entries I was just experimenting):