If you are a U.S. citizen living outside the United States, you can collect Social Security Disability Insurance (SSDI) benefits, but you generally cannot collect Supplemental Security Income (SSI) once you have been abroad for more than 30 consecutive days
I think you are stuck, just put the 800K in the savings account and don't worry about the <$600/year in 'lost interest'. Keeps your like with immegration simplier and worth every penny.
I have a minimum mint mobile USA number as an eSIM on my phone. I turn it on (over wifi) when I need 2nd). Typically a bunch of political text messages fly in also.