Perhaps God chose those plagues to prove that the gods the Egyptians worshipped had no power.
Rah...god of the sun...plague of darkness
Nephtyhs...goddess of the river...plague turning water into blood
Etc. Etc.
Interestingly.......
In Egyptian mythology,
Kek (also Kuk) is the deification of the concept of primordial darkness in the Ancient Egyptian Ogdoad cosmogony of Hermopolis.
The Ogdoad consisted of four pairs of deities, four male gods paired with their female counterparts. Kek's female counterpart was Kauket. Kek and Kauket in some aspects also represent night and day, and were called "raiser up of the light" and the "raiser up of the night", respectively.
The name is written as kk or kkwy with a variant of the sky hieroglyph in ligature with the staff associated with the word for "darkness"
Egyptian frog goddess Heket