I bought Affinity Publisher just because it is occasionally helpful, but mainly to support Serif/Affinity as they continue to develop their products. However, I wish to add my voice to the cry for support for book publishing - both in paper and eBook(although Calibre can handle PDF->eBook so that's a secondary wish). But footnotes(and endnotes), bibliography with references etc is vital. For now, I'm using MS Word - and a decent Word importer would be a step forward! - or an ancient version of FrameMaker (v6), which was the best book publishing tool ever until Adobe got their hands on it and wrecked it!
What I really would like is to use Word (or LibreOffice) for content creation then import it into Publisher for presentation. At present, I can do my cover in Publisher but everything internal has to be done in Word (or imported into FrameMaker).