Just went though the 7.92 Carcano section in Weaver.
The Italians made and issued 7.92 Carcanos to Italian troops fighting in the Soviet Union. These were repeaters.
There were German conversions (rebored and rechambered, not rebarrelled) done by/for Germany. In Brescia and by Krieghoff.
The converted rifles were not considered to be successful. Inaccurate with heavy recoil. Most were single shot, with a block of wood filling the magazine. Sights were altered for a fixed 200m zero.
Limited numbers. Conversion program was in 1945; hampered by shortage of boring and rifling machines.
Unlikely to have been Volkssturm issue; more likely police & auxiliary use.
There were other 7.92 conversions. Greek and Egyptian.
I would suggest that an authenticated German conversion would be a rare bird indeed.