Currently, the custom sorting only sorts alphabetically. It would be great to add a feature where you can sort a column based on the user input.
For example: I have a column that contains a bunch of “great, okay, bad, good, great, okay”. I would like to be able to sort the column based on “great, okay, bad”, not alphabetically.

This would be ingenious, for predefined values which also then have a predefined sort order (like ENUM datatype). Upvoted.
That’s also useful for week days, t-shirt sizes, and so on. It’s already possible to specify a “value list” for a string column, and this value list could be used as the sort order.