When making a github release, you can attach whatever file you want, including .exe and .deb. The problem is that building packages is kind of a nightmare, as there's at least one (or, as is the case far too often, many) build system for each programming language. Linux package management is also hard as each distro has its own way of packaging things. And you need a mac to produce macOS Applications...

My point is, there is no way github could add a fully automatic "build and package this release" button. It would require tons of configuration (and trial and error...) from the user.

But good news! If you _are_ willing to figure out how, you can make a github pipeline that compiles and packages your code (producing an "artifact"). Several projects I follow do exactly this. A complex problem like this essentially requires a bespoke solution, and to be fair github does give you tools to automate said solution. The problem is not the infrastructure but the complexity of build systems.

I do agree there should be more ready-made pipelines to aid this process. When I tried to release a python program to work on linux, windows, and macOS, I quickly realized I wasn't interested in figuring out how to make a working pipeline (after spending a weekend getting it to build on each OS in the first place). But surely that's because python is particularly bad at package management... Well, most languages are particularly bad at it