Only a few things to add: read about an Aussie or Kiwi "sniper" in the desert who used a K98for working close to the German lines. Presumably un-scoped, but that is a presumption.
Have never seen any photos of scoped K98s in Africa. Germans did use all kinds of other optical equipment however, and if it was usable, presumably rifle scopes would be as well. Same for our side, except our side was even more clueless in regard to sniping at that point than the Germans.
Read about an officer using a "private purchase" sniping rifle near the end of the African campaign; definitely a scoped rifle. No other details and I cannot remember the source now.
Should be possible to determine the equipment of formations from their organization: if they had a scout or sniping section, they must have had the rifles too.
If the rifles were on issue in Australiaand NZ before the war, they would have been taken along surely? Troops, even senior officers, are not typically told where they are going until they are on their way. Too late to be dropping kit at that point, unless left on ships upon disembarkation.
Better ask the vets. DAK still has an association; somebody write them a letter.
Plenty of places to snipe from in the desert in those days. Knocked out tanks & vehicles being a prime one. Rocky terrain, darkness, adjacent MG or gunfire, early morning or late evening sun glare: all good cover for a sniper I would think.