Yes, I have a Remarkable 2 and I had this issue of multiple parts to organize for my novel.
I moved the main draft to Scrivener, and now it’s easy to navigate.
But I prefer the RM2 for the nomad writing and for long editing sessions.
So what I do is that I manually “check out” the part I need to work on from Scrivener to RM2 (I have a black RM icon for those in Scrivener).
The copy - paste works fine that way: Scrivener to RM2
But when I copy from RM2 to Scrivener, I have this issue: loss of italics. So I had to write a small html/js standalone app to convert the clipboard, and now it’s fine. The tool: Paste as HTML not getting the italics (bold and the rest is ok) - #5 by LoneDraft
When the text is back in Scrivener (end of editing session), I reset the icon to default.
And for my >100 part I have a visible progress with a colored dot.
I hope this help.