Integration with other completion UIs
Several excellent completion UIs exist for Emacs in third party packages. They do have a tendency to forsake standard Emacs APIs, so integration with them must be done on a case by case basis.
If you manage to use ‘orderless’ with a completion UI not listed here, please file an issue or make a pull request so others can benefit from your effort. The functions ‘orderless-filter’, ‘orderless-highlight-matches’, ‘orderless--highlight’ and ‘orderless--component-regexps’ are likely to help with the integration.