I came across Goodbye Wofi, Hello FZF which is a collection of scripts available at GitHub, one of which can be used as an application launcher and another parses swaymsg -t get_tree to list windows and to switch to a selected window (like “Activities” but more informative because the listing has the application name as well).
The scripts require fzf and fd, and default to alacritty as the pop-up terminal.