I recently implemented nvim-scrollview, a Neovim plugin that displays interactive scrollbars.
The scrollbars serve as a visual aid, which can be helpful in addition to the position information already provided in the status line. The main features are 1) handling for folds, 2) support for mouse dragging, and 3) partial transparency so that text is not covered. Scrollbar generation and refreshing work automatically.
The plugin is implemented primarily in Vimscript, but requires Neovim 0.5 for its WinScrolled event. Additionally, Neovim’s built-in support for Lua was utilized to speed up processing.
The source code—along with installation instructions—is available on GitHub:
https://github.com/dstein64/nvim-scrollview