opt.listchars["eol"] = "❌"
opt.listchars["space"] = "❤"
opt.listchars["trail"] = "✚"
opt.listchars["extends"] = "◀"
opt.listchars["precedes"] = "▶"
picked it up from vimscript lua - Neovim lua config: how to append to listchars? - Vi and Vim Stack Exchange
Also tried reddit: