Written Egyptian is more complicated than that. Yes, there were pictographs, but there were also one-sound-one-letter correspondences, particularly with names and some grammatical forms. That’s how Champollion figured out how to read it...names in Greek were transliterated nearly letter-by-letter with Egyptian hieroglyphs in the cartouches.
And actually, there are very early inscriptions called “proto-Siniatic” that used the Egyptian values almost like an alphabet.
https://en.wikipedia.org/wiki/Proto-Sinaitic_script
Mind-blowing. The table makes it plain how many reconstructed names lead directly to corresponding Greek letters and thence to the Latin alphabet.