Hey @Errykostala !
There is a slight difference in nuance between these two grammar points. なお is used to state that something is still happening without change. 未だに is used to to emphasize that something has been happening from the past to now, without any change.
上司のパワハラを人事に報告してもなお、上司のパワハラが続いている。
This has the nuance that the speaker is in the same situation as they were before talking to HR.
スマホが普及している中、未だにガラケーを使っている人がいる。
This sentence emphasizes that there are still people that use flip phones, even in this day and age. (highlights the ‘now’ part of the sentence)
I hope that this answers your question!