Exactly.  It is the marriage partners themselves who bestow the sacrament.  The priest acts as official church witness.  If that is the case, marriages witnessed by SSPX priests (or even those witnessed by anyone else) are all valid, though the ones without RCC priests may not be canonically licit.  As for the Sacrament of Reconciliation, it is God Who extends pardon, not the priest.  God forgives us as soon as we sincerely ask for pardon - no witness is required.  We go to confession not to receive forgiveness but to show solidarity with the Body of Christ and to acknowledge the damage we have done to the People of God.