Not receiving any response, I contacted Google via the GAE Admin support process. Here is the conclusion of the Agent helping me (after he spent quite some time investigating): "Thank you so much for waiting, I was unable to find the details related to Google App Engine console, So I can confirm the account **** (email deleted) account will go away completely."
This is how I phrased my question to the Agent: "If I let my GSuite account expire and move to Microsoft 365 for my custom email domain and app/drive features, will I still be able to access the Google App Engine console/products ?? IOW: will my **** Admin account login stay active for GAE (Google Cloud Platform) ?? Or does **** account go away completely because I no longer use Google Workspace ?? TIA, Steve"
Presumably one's access to GAE Admin and Google Cloud Platform would need to be re-created since all links to the email used for GAE and GSuite get deleted. Ouch.