While using something like Advanced Query Loop can cover a lot of bases you might still need some highly dynamic or custom queries for the query loop block.

It would be very useful to have a method for registering custom queries in PHP that are effectively pre_get_posts hooks, that can be given a human readable name and selected from a dropdown in the core/query block settings.

Ideally the custom loop should be represented in the editor as well as when previewing or viewing the website frontend.