This is good, Dave. I always like to know the history behind various literary works, and the lives of the people involved. This time, I can read all about Petrarch, without spending hours in the library behind a book, or more likely screen.
Sonnet comes from the Italian word sonetto, ie a little poem, and like the English word song. There is no reason they should end in the 17th Century, no reason we can’t write them today.
Good on you for researching this.