I rate my Ortlieb Ultimate bar bag as waterproof with the caveat of not chucking it into rivers, seas, ponds etc.

A camera liner is an optional extra.

https://www.ortlieb.com/en/ultimate_camerainsert/

Having determined my bag is not going to soak my gear, I'll be hauling my Nikon next tour.

I've just got to work out what to do with all the crap I normally put into the bar bag which I don't want bouncing around scratching my camera or lenses.