Are you guys telling me I can install Mavericks on it and it'll work as it should?
If what chrfr is true, and the 2015 and 2017 MBA use the same (or very, very nearly the same) logic board, then yes, it'll technically work. However, you won't have graphics acceleration, and you'll need to use a USB mouse and keyboard. The latter problem may be fixable, but no one has done it. I'm not sure I'd call that working "as it should."
If it is possible could you please provide me with a link where I can read all the details.
I have a 2015 Macbook Air. The earliest version of macOS this model ever shipped with was OS X 10.10 Yosemite. However, I want to try installing OS X 10.9 Mavericks, because Yosemite makes my eyes ...
apple.stackexchange.com
And in the end, is it worth it once graphic acceleration, trackpad and keyboard wouldn't work properly?
I don't think it is, sorry. You can't really use it as a laptop since you have to plug in an external keyboard and mouse, and macOS really sucks without graphics acceleration.
It might be fun to play around with for a bit, but that's all.
If you're crazy like me, you could have DoubleDex swap out the logic board for you, like they did for me. There's basically no performance difference between the 2014 and 2015 MBA (which again according to chrfr is the same as a 2017 MBA), and Mavericks runs perfectly. No regrets on my end.