The two lines you cite here as from Sappho Π2 25–26 are in fact very poorly attested on the papyrus. They are mainly reconstructed from a quotation in Athenaeus (15.687b), which is relevant because he understands Sappho’s “love of the sun” to mean her love of life (ἡ τοῦ ζῆν ἐπιθυμία). He therefore interprets “of the sun” as an objective genitive as well.