I don’t know about canning bacon but an old man (really really old) told me that when they killed a pig his mom made sausage. She cooked it all, packed the patties in jars, poured the hot grease over the whole mess, and slapped a lid on. He said the hot grease preserved the sausage, no pressure canner required.
I never tried it but he swears the sausage stayed preserved and sealed.