Jamieson, Fausset and Brown on Hosea 9:3

3. return to Egypt--(See on Ho 8:13). As in Ho 11:5 it is said, "He shall not return into ... Egypt." Fairbairn thinks it is not the exact country that is meant, but the bondage state with which, from past experience, Egypt was identified in their minds. Assyria was to be a second Egypt to them. De 28:68, though threatening a return to Egypt, speaks (De 28:36) of their being brought to a nation which neither they nor their fathers had known, showing that it is not the literal Egypt, but a second Egypt-like bondage that is threatened.

eat unclean things in Assyria--reduced by necessity to eat meats pronounced unclean by the Mosaic law (Eze 4:13). See 2Ki 17:6.