It's really a great and flexible editor, with a couple of rough corners, but overall the only serious alternative to the above-mentioned editors. And since it has a sensible licensing model it is an overall good choice.
It might be somewhat similar to the "details" extension, but they were also drag and droppable. The drag and drop support was also somewhat subpar compared with TinyMCE, I ended up using vue.draggable.next to solve the issues, but this added a layer of huge complexity.
Then there was an issue that the UniqueID is a Pro extension and it would have been required for properly storing the document. I now see that pro extensions are free, after registration, but I'm not sure if it was always like this, I think it was coupled to a GitHub sponsorship back then (maybe around August 2021). For a side project which would then sit at rest for some months this wasn't feasible. I think I implemented a custom UniqueId to get around this, but I haven't touched the project for over a year.
About 2 months ago I was thinking about rewriting it in React and see if I could turn it into something, but I haven't found the time.
I hope you'll find the time to continue your project.