When you cloned our repo, you got 10 years of specific work on common work and that was contributed by 500+ people. Most of people are resolving their specific problems, yes, but we all try to do it the way that is reusable, that person behind has less work. We also got a lot of things prepared. Doing things universal should always be considered. Also because you might get help from someone. Which has absolutely same problems, but is having hardware from another vendor.
In our world, SoC defines how things work, not the one that put SoC on PCB and name / sell it. This means that most of the drivers are the same, especially this area is shared - low level communication protocols such as GPIO, I2C, SPI. This is always shared among boards with the same SoC. This goes further. It is shared among same families and we also already have some common generic top level API / libraries that can be used. https://docs.kernel.org/driver-api/gpio/consumer.html (but here my understanding ends, I am not updated with the state of this)
Yes, it has no point poking into. WiringPi library is a dead project for many years and its no point dealing with this. What vendors do here is, trying to be "as Rpi as possible", so they are doing their quick and dirty assemblies of that, always with partial functionality and absolute absence of maintenance. Their goal is to sell, regardless what is the quality of software. Is that your goal? I doubt.
I am not an expert in this field, so those are general tips, but there are people on and around this forum that knows this stuff well, as they developed those libraries.
I am just giving you some ideas / tips. Decision what you will do with your time is yours.
Another one that came into my mind, while replying: https://github.com/eclipse/mraa