Good find! Those are exactly what’s used, except they are M6 size which seems to be unobtainium (everything I see is FUB) unless you know the Chinese words for “elevator bolt”.
However, I insist those aren’t the bolts you’re looking for. The ones you showed a photo of at the top work better in my experience.
Go with “M6-1X25 ISO 8.8 Metric Carriage Bolt DIN 603 Zinc Clear” and snatch some M6 nyloc nuts and some M6 x 12mm x 1mm brass washers and this works better for me than the stock enertion hardware.
If you want the pulley a tad closer, grind or file off some of the bolthead or pulley where it interferes. I don’t have a photo handy but I find that works really, really well. And it’s much stronger than the stock hardware.