You can already do this in vim. Pretty easy to shell out to whatever command you want and use the result for various purposes.
For example, I really like the "select then edit" approach of Helix, but Vim doesn't really play nice with that (there may be better plugins since I last looked to be fair). File handling, buffer rendering, and frames have very little to do with that, and yet I have to switch editors, lose all my plugins and configurations, and switch all those subsystems at once.
There's missed opportunities for modularization.
Edit: looks like Neovim is already split from its UI.
FWIW though if that's what's important to you, I get the sense that kakoune is much more vim-like in making it easy to compose with other tools, while being set up for your preferred editing model.