@barisonat7 To answer your accessibility question, both Wix editors’ support accessibility out of the box.
In both EditorX & Classic Editor, Wix does use the native HTML under the hood for the dropdowns. It’s setup nicely for accessibility already.
I do have some news for you though. If your goal is a must that you self-host the website on other servers, Wix would not be the platform to facilitate this. The hosting of the sites is part of the package when you get the rest of the ability to develop using Velo etc. I’ve had to make this choice myself, and keep finding myself choosing Wix hosting for most things :). Hope this helps you get to your goal.