@afre this was the other thread you were referring to:
It’s not exactly the same thing as @klikkk is asking for, but the two would be complementary. Use the tool requested here to create an arbitrary collection, and then use the tool requested in the other thread to put the arbitrary collection in an arbitrary sequence.
It seems to me like a lot of duplicated effort to put something like this in DigiKam and in darktable and in whatever tool someone turns their eyes to next…