Best effort.

Binary Qt and GTK apps compiled even 10-15 years ago often still work, and do so on almost any distro. Games are a bit more iffy, depending on if it used SDL or not; and Steam on Linux has made great effort to make the (admittedly few) older Linux binaries remain alive (and if Steam doesn't, the community has).

I don't see this as an issue. Using Linux implies a level of competency from the customer, and I'd rather help a competent Linux customer try to get my stuff run on their odd distro (ex: Alpine) than help an incompetent Windows or OSX user. One gets me a customer for life, the other just reminds me that hell is other people.