Saturns have two protection schemes.
1. They have region protection, which is controlled by in-band data in the ISO-9660 filesystem. You can a) Use a tool to change the region of your ISO image and reburn, b) install a hardware switch that changes the region jumpers on the Saturn motherboard (this is a fairly easy soldering job), c) use a cartridge that defeats the region protection in software.
2. Copy protection. This is a special track on the outside of the disc that cannot be copied normally. It is read both during the boot logo when direct booting, and in the system menu to determine if a disc is bootable. Your options to defeat this are a) swap trick -- pretty easy, just swap in an original of any region whenever it seeks to the protection track. This is a really forgiving and easy swap b) modchip -- inexpensive and easy to install
The Dreamcast region protection is also in-band, and you can modify it however you want when you're modifying an ISO image. You cannot, however, burn a GD-ROM as nobody ever released consumer burning hardware for the format. Consequently a Dreamcast modchip is only useful for booting ORIGINAL discs from outside your region -- and you can use a bootdisc too boot them instead.
All current Dreamcast backups use hacks to inject code when the Dreamcast reads data from CD-ROM formats that it supports. Most older dreamcasts support the Mil-CD format, which supports directly loading code. Later hacks had to use a different technique, but there are boot techniques that work on every Dreamcast ever manufactured.
Most later-released selfboot backups will therefore work on late-model Dreamcasts -- and those that don't can be booted with a bootdisc that does.