With a waterbottle handlebar mount you can Make most any bag you find into a handlebar bag

I got 2 6~7cm long 5mm bolts and some plastic spacers, and some fender washers and bits of plastic sheet for stiffeners.
and It worked fine .

will admit Ortlieb bags are excellent Have one its on my road bike , RC roll closure top.
a discontinued Ortlieb Camera Bag serves on my Trekking bike, adapted by using a KlickFix support wire frame .

Klick Fix Plate Mounts are used on Carradice Super C handlebar bags , another good ,modest sized HB bag.
Berthoud for the Francophiles , offers a KF mount bag too.