OpenGL is being sunset, no one cares about Metal, and the only people who voluntarily write Vulkan are bearded code wizards taking the weekend off from writing the kernel.
There's no end of frameworks and engines out there, most unfinished, and all extremely opinionated about what your code must look like. ("You will build scene trees that hold callbacks. Actually no, you will write entity and component classes and objects. Wait, forget that, everything is immediate mode and functional and stateless now!")
Add all the platform nonsense on top (push notifications for a mobile game? In-app purchases? Mandatory signing via Xcode?) and it's all just a hot mess. There's a reason Unity has the market share it does, and it's not because it's a fantastic piece of software. It's because cross-platform for anything more complex than a glorified web view (which is, to be fair, most non-game apps) is still a massive pain.
There's no end of frameworks and engines out there, most unfinished, and all extremely opinionated about what your code must look like. ("You will build scene trees that hold callbacks. Actually no, you will write entity and component classes and objects. Wait, forget that, everything is immediate mode and functional and stateless now!")
Add all the platform nonsense on top (push notifications for a mobile game? In-app purchases? Mandatory signing via Xcode?) and it's all just a hot mess. There's a reason Unity has the market share it does, and it's not because it's a fantastic piece of software. It's because cross-platform for anything more complex than a glorified web view (which is, to be fair, most non-game apps) is still a massive pain.