how can I get config data into serialized pulumi functions. for example like

cfg.requireSecret()

. currently it just serializes the literal function, but not the value

Is this for use in a lambda or similar? You can't use Pulumi code from lambdas (or at least, you couldn't last time I tried...). Instead, put the value into something accessible at run time, like SSM Parameters, a vault, or similar. Then the serialized code should use normal AWS SDK to retrieve that value.