How do we handle huge models and QHeaderView section move

This is a discussion issue for:

(1) https://codereview.qt-project.org/c/qt/qtbase/+/575360
and
(2) https://codereview.qt-project.org/c/qt/qtbase/+/582668

We have quite a few reports on QHeaderView taking too much memory on huge models (e.g reflecting an extremely sized Database Table). This is fixed by (1) - that however emitted sectionMoved for moveSection (and swapSection).
The issue is that a DB table (and model) can often easily change the order in the model.

That leaves us with the following questions:

• Should we have huge model as a flag in the Model itself?
• Should we handle request of sections in the model - and how (API or flags)
• If we don't use the model then how should we handle the move of sections?
• Should the QAbstractItemModel itself support move (and maybe swap functions)?