Well my firstribit of downloaded Linux Mint XFCE iso worked fine and includes save2flash. I haven't yet made the planned second firstribit to handle final PLUG extension builds; that will come later.
Since Linux Mint FR build worked that means most of the other distros catered will too, so the facility almost ready to hit the streets again.
@wanderer The trouble with including iso build code, which is only needed to convert an already built and bootable frugal install is that it adds an extra host build system requirement: the host system has to have iso-making software installed, and various other bits and pieces concerned with EFI booting and so on. Usually that means you almost 'have to' use a certain type of Linux host specially thus prepared. FirstRib was designed to be like LEGO - one simple script to build the root filesystem, then add the vmlinuz, modules, and firmware, and finally FR initrd to boot it in a frugal install subdirectory.
In that LEGO-like fashion, making an iso is an optional extra stage (script) and one that has that special host build system requirement. As it stands KL/FR distros can be build on pretty much any Linux system, whether they include iso-making software or not. Maybe someone will make a script for creating an iso out of a KL/FR distro, but that depends on them; but will be a separate script probably since optional. Of course it is trivial in bash to write a glue everything to do frontend script...
Really, FR is a simple to use build system already. Many of the existing KL distros are in fact published via a single script builder, but no iso making is currently part of that though you may find it difficult to understand why. Simplicity is the overall reason - making an iso involves quite a bit of extra work and no-one bothered scripting that so far since pretty low (unnecessary for most of us) in the list of priorities actually. In practice, developers who want to publish distros either know how to make isos out of their build creations or soon find out how to (though some no longer care to.make isos of their work anyway).
KL/FR often provides a simple single script such that pretty much anybody can make a KL frugal install, which is more useful for most people (aside from the likes of Ventoy users who tend to want an iso made for them). Yes, I know, DebianDog script will, with suitably installed iso-making software, include making an iso for you, but what do you use the iso for? Don't you usually just make a frugal install with its contents??? If so, why need an iso anyway? But this is part of another story maybe - and has been discussed already on other threads concerning whether it is worth making iso releases nowadays.