The answer you got today at Thai Immigration is correct.
And with borders closed a bounce is not possibly.
To obtain a one year extension of your O-A based retirement...
You need to show 800,000 Thai baht in your Thai bank account.
Plus proof of health insurance issued by one of the approved Thai Insurance companies.
As its already August 5th...it seems difficult to meet the financial 800,000 Thai baht in Thai bank requirement...
as it needs to be seasoned two months before you apply for an Extension of Stay for one year.
You will be on amnesty until September 26th.
Following the O-A permission to stay date expiring August 18th.
Possibly
@Tod ********
may have a suggestion in the morning for you.