Interesting. I’m in the western U.S. and have never heard
Megan pronounced with the first syllable rhyming with “peg”, always rhyming with “
Ray”.
As an aside, when I took a look at Forvo this morning, I found a “Welsh” pronunciation of
Tegan using “tee”, but it was provided by a person in
France. I did a second search and found a Welsh pronunciation for the phrase “brics tegan” provided by a person in Wales using “peg” :
https://forvo.com/word/brics_tegan/#cy
No idea whether the word “tegan” in this phrase has any connection to the name, “
Tegan”, but there it is for you, in case it’s of any help.