For copy-pasting text to/from the terminal, I prefer to use Mac shortcut Cmd+C. It doesn't work out of the box on Linux (you have to use Ctrl+Shift+C, because Ctrl+C sends SIGINT). But there's a simple way to make Cmd+C work universally across all apps by rebinding Cmd+C to send Ctrl+Insert and Cmd+V to send Shift+Insert. It turns out these alternative keybindings work everywhere (browsers, GUI apps, terminal, etc). I use keyd to do that in software, but some QMK keyboards can do that rebinding on the keyboard itself.

This is my keyd config:

  [ids]
  *
  
  [main]
  capslock=overload(control, esc)
  leftalt=layer(meta_mac)
  leftmeta=layer(alt)
  
  [meta_mac:M]
  c=C-insert
  v=S-insert