DPE leaf only has ECC keys and certificates how this will do MLDSA SIGN

https://github.com/chipsalliance/caliptra-mcu-sw/blame/9633aa39a698ab3f32aafd678459c96c057fbd95/docs/src/external_mailbox_cmds.md#L65C3-L65C138

DPE leaf only has ECC keys and certificates how this will sign data using above mailbox command(MC_MLDSA_SIGN)
also, why DPE Invoke has sub command Sign, how is this different from that Sign command?