Layout > Page numbers: 1 / i / I / a / A and a first-page number, both
round-tripping. ODF has no document-level start — probed, LibreOffice
puts style:page-number on the first paragraph's own style — so the
export mints one there and the page layout carries style:num-format;
Word takes both in the first section's w:pgNumType. The page *count*
field stays decimal, as the one both of them write does.