Tiny success: after banging my head repeatedly against the desk over thinking I had to arrange the zine pages myself in a "print layout for folded double sided pages that will actually reflect the intended page order and not some horrific mutant" guide?" and getting a kind response (thanks Stacy) and guide, learning that they're called "impositions" (indeed), I did further research and found that Affinity Publisher does it for you in the print / export to PDF settings thus relieving copious stress and much hair pulling even though I already cut my long covid-hair back to a short summer cut because my black hair in the summer makes me yearn to go grey which, in spite of life’s best efforts over recent months, has yet to happen.