I find it really confusing that during the alphabet-learning stage at times it's requested to translate a word, and at other times requested to just write a letter as 'omicron'. It's counter-intuitive and I think it would be more useful to do letters first, then slowly after doing the alphabet start with small words and only then the meaning of those words.
Don't judge the Greek alphabet by the standards of the Latin alphabet. They developed differently over the millennia.
So, basically the "γ" in "γράμμα" is pronounced as a voiced velar fricative?
Yes, it is the voiced velar fricative. In fact, that's the very letter the IPA uses for the sound.
They don't have the Greek alphabet when they want you to translate the text.
My mum taught me the Greek Alphabet: the ni is ok : alpha beta gamma delta mi ni xi omicron pi ro sigma taph or taf, I talk Spanish my Greek is no perfect but I can distinguish. E G omicron should sound o mi cron that is MI never can you say omocron it is not o mo cron.
CA/US keyboard, type: To gramma n
Greek keyboard, type: To gr;amma n
('N'(uppercase)/'ν'(lowercase) is the 13th letter of the Greek alphabet)