visible history is tied to key 1-0 thus 10 entries as historically used by home screen and other menu shortcuts, Favorites can be a longer listing and I used those in the past, there was an experimental use of vbkm (now dropped, that provided for nesting groups)

currently the Ctrl+K list may offer more than 10 at a time

It is fairly easy to write a list in the operating system for your own use that calls SumatraPDF to open any of thousands of grouped pdfs but that's same as any document manager library usage.