I managed to install QEMU virtual machine running Debian 12 arm64 and package Gambas 3.19.5.
If I had a webserver I would provide you a link to add to your /etc/apt/sources.list file and a simple apt-get update && upgrade would do the trick for testing it on a real arm64 system running Debian12/Raspberry Pi OS (64-bit).
Instead I have a gitlab where I publish archives of set repository and the DIY instruction to set it up as a file repo on your local system (kinda like a permanent cd rom repo) or set it up using apache2 webserver as an online repo (either in a local network or on internet, concept is the same).
I hope someone likes the DIY acpect of this (if you are on arm, guess there is that drive

The current Raspberry Pi OS (64-bit) is based on debian 12 arm64, so gambas packages should be compatible as the architecture specific packages where compiled on debian 12 arm64 architecture (simulated)
Link to archive that has repo with arm64 for debian12: https://gitlab.com/gbWilly/gambas3-debi ... ian.tar.xz
It is a downloadable archive. Once unpacked you will find instructions on how to set up as file or as web repo.
The repo contains debian 11 i386 and amd64 gambas packages and debian 12 i386, amd64 and now arm64 gambas packages.
If you test getting the repo setup and installing gambas 3.19.5, please report back successes and failures, so stuff I know where I am at on improving.
I'll be looking into installing debian 11 arm64 in QEMU to make arm64 packages for debian 11 as well. These should run on Raspberry Pi OS (Legacy, 64-bit) as this is based on debian 11.
Fun thing is, once the VMs are running and proven to be providing usable packages, updating to newer versions will become easier.
I plan on automating, at least big parts, of the whole packaging setup, as up till now I just manually did it over and over again (perfect for getting the needed insides of making the perfect automated code

I've done every step and documented every detail, with automating in the back of my mind, from retrieving the most recent version of gambas from git up to publishing a repo on some webserver and all in between.
Looking forward to some reactions and if my packages for arm64 actually work.
The other architectures I can test on real systems, but arm64 I can't.