Same here. I have my own domain set as the main email address of my personal Google account (I have in fact deleted the Gmail one altogether, as I noticed that otherwise some websites would still pick the Gmail address over the custom domain one when using SSO). Not many people seem to know you can do this without Google Workspace, or that you can have a Google account without a Gmail address.

If I ever lose access to my Google account I can just set a password through the "forgot my password" feature (I've noticed this is often also the only way to set a password if you create an account through SSO with some websites, but it does work). The convenience of SSO with an escape hatch as you say.