Hi, thanks for the answer.
Your solution (at the end) is exactly what I was looking for!
Yes I am familiar with backward compatibility. But, literally, in this case, I can NOT go back to either 16.04 or 18.04. The reason is my development platform is the Lazarus / free pascal project. I absolutely love this project, the IDE is wonderful, etc. But. It is a work in progress and the versions available for development in 16.04/18.04 make it extremely unfeasible (due to bugs in localization) to go there based on my project needs.
So what I want to do is, yes, build around this “modern” 20.04 release. But, I do not intend to do this every year. In other words, in around 2028 I will be eligible for the Appimage Hub because then I will be supporting the “oldest” still supported release.
I want to get into the sytem now and go forward, not go 4 years back. This does actually pain me, I agree it would be wonderful to be able to run on 16.04’s. But my trade-off in this case was that I had to face the reality that my software couldn’t be released in this method at all, and I’d have to look for other (flatpack/snap/normal) packaging methods.
I will be downloading and testing the -s switch, so a really big thank you for providing that!