Edit: There's this summary, but nothing detailed so far:
Continue using your custom domain with Gmail
Keep using Gmail with your custom domain
Retain access to no-cost Google services
You will retain access to the no-cost version of Google Workspace services such as Google Drive and Google Meet, and additional Google services such as Google Search, Google Maps, and YouTube
Keep your purchases and data
You will retain access to paid content such as movie purchases at Google Play and data stored on Google Workspace
This option is for non-commercial personal use
Google may remove business functionality from this offering and transition businesses to Google Workspace. Additionally, this option will not include support.
Maybe this really was supposed to be some sort of "shock" to push a certain group over to google's paid services. Or maybe it was just a mismanaged mess.
Theory 2 is they really were developing a GSuite to Google Account migrator and it ended up being way too messy to be workable in the deadline they set themselves.
Funny how some (arguably futile) memories stick in.