I take that recent rule changes by Singapore Government on Americans who is not able to get digital certificate as a positive development (look like they realize it's still hard for many Americans to get that)... It seems not going to be tough for people to contact their state's department of health for record. I live in PA and I have copy of my vaccine immunization record from PA's Dept of Health and I guess I have to use that document if I decide to go Singapore next year.

It seems far easier than trying to get your vaccination provider to fill out blanks that will make Singapore government happy...