Shippy provides the following feature support for USPS.
To use USPS, you'll need to connect to their API.
clientId with the Shippy carrier.clientSecret with the Shippy carrier.To create labels, you'll be required to supply a few more details.
use verbb\shippy\carriers\USPS;
new USPS([
'isProduction' => false,
'clientId' => '••••••••••••••••',
'clientSecret' => '••••••••••••••••',
'accountNumber' => '••••••••••••••••',
// Required for labels
'customerRegistrationId' => '••••••••••••••••',
'mailerId' => '••••••••••••••••',
]);