How to mark a certificate as a trusted introducer

To mark a certificate as an exportable trust introducer (a certificate authority) for the domain example.com with a preconfigured trust depth of 1, use sq pki vouch authorize as follows:

$ sq pki vouch authorize --certifier $FPR_CERTIFIER --cert $FPR_TO_BE_CERTIFIED --domain=example.com

Read more about how to certify and authorize certificates.