While I do understand your wish to use Joplin as a replacement for Scrivener, I have to say that these 2 products are nothing alike.
Scrivener is a screen writing and novel writing software. I’m using it myself on macOS, but not for managing notes.
Joplin is a note taking application. Misusing Joplin to replace a specific feature set will never work. Some people have been trying to use Joplin as a content management system. You want to use it to write novels or for play writing. In either case, Joplin will neither do these things well. Why? Because it is a note-taking application and it should stay a note-taking application. Otherwise half-backed solutions will creep into to product to accommodate a few other feature sets which in turn will make the note-taking part of Joplin worse.
Don’t get me wrong, I want Joplin to get new features, but not if they compromise the primary function of Joplin.
There has been a feature request to allow tabs to open several notes simultaneously. Should that ever be considered, I guess a split view could be the next step.
Text files are most likely not going to happen. Markdown is already a text format. Nobody forces you to use markdown syntax. You can always write plain text.
Yet again, it is not LibreOffice or Word, nor Scrivener.
Please keep in mind what Joplin is: a note-taking application.