Long story short: I bought a domain via Google Domains (beta) with the intention of using it for my personal site/blog that I made using Google App Engine. When using GAE to make a site, the default domain is "_[site name]_.
appspot.com". Since I need something more simple...preferably the domain that I already purchased, this needs to be changed. Honestly, the site build has taken a fraction of the time spent trying to figure out the domain swap, which I thought would be a painless last step!
I have been going back and fourth with the team at Google sites for weeks and was just told that they do not know how to solve the problem. So they pointed me to this forum where I might be able to find some answers.