Basically any data grid that implements multiple AND/OR filters at column level, sorting, reordering, infinite scrolling, virtualization for handling large amounts of data, etc. Also handling basic pending / error / retry states (things that I take for granted with React Query).
Yeah, a data grid is a good example of a complex hyper-interactive component. There are people out there who have made them with Web Components, which can be dropped in and used in htmx projects when used correctly.
Re: request states, handled very nicely out of the box by htmx with a little knowledge of attributes like hx-indicator and JS event handlers to handle htmx error events.