What is the correct pronunciation of YHWH, God's revealed name in the Old Testament? What is the correct pronunciation of Jesus' name, as it would have been pronounced in Hebrew? Why do some groups make such a huge deal about the names of God and Jesus?

Links:

What is YHWH? - https://www.gotquestions.org/YHWH-tetragrammaton.html

If His name was Yeshua, why do we call Him Jesus? - https://www.gotquestions.org/Yeshua-Jesus.html

What is the meaning of Yahweh? What is the meaning of Jehovah? - https://www.gotquestions.org/meaning-of-Yahweh.html