Fun challenge! I don't know if the Python tool counts as a one tool solution or not, but I wanted to try tackling this using Python to get some practice using the new tool! I also tried using just base Python (except Pandas to create a new dataframe since Alteryx can only write out dataframes) and tried to avoid using regex. I also added one more phrase "It's going to be a great great, fun-filled day day!" just to make sure I was still capturing the correct punctuation mid- and end-sentence.
Beat my head against the one tool solution for a while but finally got is. I included the basic tools solution as well.