Not seeing any issues in aws-us-gov.
Has it's own version of everything, physically segmented, even for global systems such as IAM.
You have to be a US Citizen to work on it and you need special security clearances.
GovCloud customers only need be a US person or entity, beyond that any further regulatory alignment is up to the customer. AWS does not audit the IAM user base for nationality or any compliance requirements.
Disclaimer: I am an AWS Public Sector Solutions Architect.