So for using Haxe Kha toolkit if you want 2D then you may draw a rectangle
NME is pretty similar.
Each toolkit has it’s own ecosystem and approach to multiplatform but they will all support linux and android. OpenFL is the most popular, NME is pretty similar written by the C++ expert, Heaps is less flash like written by the Haxe original creator, and Kha is more shader approach focused, so low level, and provides the most support for alternative shader pipelines rewritting your code for Metal, OpenGL, DirectX etc…
You can also use C# or Java and they can help you build externs to work with existing solutions but the haxe toolkits are likely better approach.
While you can compile a list of advantages it’s very much down to personal preference and if a toolkit seems to be setup well to target the platform you need, with effort any of them target pretty much anything and any of them are just as suitable.