I have no problem with them being angels or demons (a minority opinion on this psalm), but not deities, which is something different.
With regard to Exodus 12:12, we have the following commentaries which aligns with the other:
Gods, idols, whose statues some assert were overthrown (St. Jerome, ep. ad Fabiol.; Eusebius, præp. ix. ultra[last]); or sacred animals, which were adored by the Egyptians; (Origen) or the word may imply that the princes and judges of the land would be mostly destroyed. (Calmet) — Forbes observes, that by the destruction of the first-born, all the proper sacrifices, and priests of Egypt, were destroyed.