I have just tested my app against the newly released Ubuntu 19.10, default install being Gnome of course.
Results seem a bit disappointing, there is, I suggest, a lot less GTK2 stuff in there compared to previous versions. In particular, a basic Lazarus app fails at startup complaining of missing libgdk-x11. Interestingly, I cannot find such a library in the appropriate repo. Assume its bundled in with something else.
I normally tell my end users to ALWAYS use dgebi to install a local or downloaded file as its good at resolving dependencies. (Apt and dpkg are not when the deb file is sitting on your local disk). Fortunately, gdebi must be built using similar gtk2 dependencies as our Lazarus apps and installing it first results in all the necessary libraries being installed.
I note that some other non Gnome Distributions are indicating they will be leaving out GTK2 stuff as time goes by so its not just those (expletive deleted) Gnome devs at work here I am afraid. Sigh....
If your install model is not deb based, its something you may need to watch out for.
When I have some time, might build another VM and try and workout exactly what missing libraries a minimal Lazarus app is dependent on in this brave new world.
Davo