SDL will be adding SDL_OpenURL() in version 2.0.14. It's still pre-release, but it checks out on Win10 (opens url in default browser not IE). If it works on all supported platforms after the next SDL release, all of the platform specific openWebBrowser() calls can be eliminated and replaced with a single SDL call. https://hg.libsdl.org/SDL/rev/d0348dab7c0f
See line 3.45.