I have a need to filter many records by the day of the week derived from a date-only field in those records (i.e. not today's dow).
I would like a solution that works with views filters, as the wider context is that the view itself is being manipulated in code to supply which days should be included -- note plural. Basically, a paragraph is configured with List(text) fields for the weekdays and during preprocess the view is loaded and the field values 'poked' into the view's value instead of the fixed original value. Several other fields are updated likewise.
If I was doing this in plain SQL I might use DATE_FORMAT(fieldname, "%a") IN ("Wed", "Fri") or something similar. I have looked at various existing modules - views_dates and views_date_format_sql in depth - and have noted D7-only views_dow. However I can't quite see a way forward using those (even as a base), partly because I'm not very familiar with views internals.