This required some adaptations before making the .iso.
First, I made a new Gambas3 repository that, besides Gambas, will also include all future GambOS applications (for now just GambOS DashBoard).
So, now GambOS Dashboard is a signed part of the local file repo and can be installed using regular Debian methods (like apt or synaptic package manager)
This first step was needed to ensure that not only Gambas3 is pre installed, but GambOS Dashboad as well.
Secondly, I had to add this new repo to the template used for building the .iso (template basically being a folder structure) and adapt some code in a hook (a script also in the template) to make it work.
Thirdly, I had to make sure that GambOS Dashboard will launch at login, so again some modifications/additions to the template.
The last step was to ensure that GambOS Dashboard is part of panel, so yes, another modification to the template.
After all this I run a new .iso build process and next run the .iso as follows kvm -cdrom gambos-bookworm-mate-amd64.iso -m 4G.
Guess what, the live boot did exactly what I wanted, Dashboard starts and panel is adapted. Below a screen of Live boot GambOS build 14.
The GambOS tour can be taken, as that part is finished (for now). New additions to GambOS will require adding to the tour in future GambOS DashBoard releases.
The 2 other buttons, in future, should open new applications (GambOS Software and GambOS Learning), but these still need to be created..
For now, all that remains is install GambOS from .iso in a VM and see how that goes. If that goes just as well, I will be making some installations instructions (it is an auto-install, but some options are left open, like user password for example). And next fase is a Pre-Alpha 1 .iso for testing purposes and find me some people willing to test the pre release and give some feedback.
Enjoy...