awk and sed have always been intimidating for me with that cryptic syntax.

Done! Chack out the latest version.

I’ve been thinking about a “create new service” feature but I’m not sure about two things: 1.how useful it can be 2.how to implement this to actually make life easier for end users

Adding a generic template would not be difficult.

No. It just reads and parses the contents of /boot/grub/grub.cfg and updates /etc/default/grub

Yes, it only reboots into the selected entry ONCE without changing the default one.