Turns out, the real difficulty is getting the current selection and then inserting that at the cursor, who knew!
//Jul 26, 2021
//Sep 15, 2019
Further Tmux setup tips and tricks with Zsh and Vim
//Aug 1, 2018
//Jul 23, 2018
Utilising the NeoVim and Tmux active / inactive window styling
//Jul 9, 2018
TL;DR: Use a Fn key bound to Applescript, disable conflicting keys, manually run the script for every app that you own.