The J is pronounced as an English "J" ("jay").
ψ – psi – pronounced "psaai" (as in "top side") or "saai" (as in "side").
from "Pronunciation of the Greek alphabet in English":
https://jakubmarian.com/pronunciation-of-the-greek-alphabet-...
ψ – psi – pronounced "psaai" (as in "top side") or "saai" (as in "side").
from "Pronunciation of the Greek alphabet in English":
https://jakubmarian.com/pronunciation-of-the-greek-alphabet-...
And I wonder how useful symbols like æ ə ʌ are to people asking how to pronounce Greek.
So...why don't we spell all languages with that alphabet? Think of the increase in efficiency!
My doctor has signs and other notices that you should arrive 15 minutes before your appointment. I asked "why don't you just make all the appointments 15 minutes earlier?"
Generally speaking, the Great Vowel Shift did quite a number on anything originally Latin or Greek.