I totally agree. Get them US passports (must ship both parent's citizenship certificate), then apply for their SS cards. (I did that for my daughter. Just beware of sending passport over mail to SS office. I did that back in 2020 due to pandemic. Envelope got misplaced between boxes in local SSA's front desk for months! A total nightmare.)
And then consider applying for their Application for Certificate of Citizenship (N-600). Expensive, but will help them to get their passports in the future without relaying on their parent's citizenship certificates, and other potential issues.
Had my N400 interview today and it went so well and smooth.
Got a notification after the interview about been placed in line for oath ceremony!
Wishing all the best.