OP, I've been working on a very similar thing for some years now, too. I could write a book about this at this point, but I will avoid gushing here.
Please let me share some pain.
Many developers/companies make this thing and none of them really know how to (or can) share. I'm happy to share my list.
The end result, as I see it, is a fragmented mess of either partially completed or fully completed and walled (and/or poorly modularized) software.
Take for example VS Code's tree view. Can a developer with a need for an explorer view just use VS Code's tree module? Not hardly. Go reinvent.
Contrast that with CodeMirror. If you look, you will see CodeMirror everywhere. This software truly empowers devs and it has resulted in pure awesomeness.
There's no shame in not open sourcing what you've created, I'm assuming you haven't. And I can't say anything about how you have modularized your components.
But it pains me that the next dev who gets an idea like yours will either give up or spend 6 years struggling to create the same thing (except the CodeMirror part).
Worse, Microsoft can afford to struggle and or throw people/money at this. They can pay people to work full time. They can give away their editor(and more) for free. That's a win from user's POV.
Are you aware that VS Code runs on GitHub and does the majority of this kind of thing? I think they could completely shut down all sandboxes or similar kinds of software from a financial perspective.
I said I wouldn't write a book.
Anyways, I strongly appreciate what you have done. It looks great.
I wish we lived in a world where we could work on the same team building this kind of thing.
My best wishes to you on getting paid to do it full time.