The have their own Hierarchy, Churches, Canon Law. They are a petit ecclesia and their illicit masses are celebrated in the Jurisdiction of Catholic Bishops - directly condemned by Trent.
From "The Jews are cursed" to "the N.O. Mass is evil" to their sspx marriage tribunals, the sspx is a heretical, and schismatic collection of antisemites and theological blockheads and, back when he was a Cardinal, Ratzinger publicly noted their intellectual and theological defencies vis a vis the Mass. He used a phrase dimplomatically that really parsed as "they are idiots"
Nice try but schismatic agitprop doesn't work with real Catholics
I have truly been concerned about a friend of mine as her antisemitism has grown every day. I sort of excommunicated her from my life for a while but then when her family talked to me and expressed their extreme concern for her I made the promise to love her where she is and that they should too and hope for the best. Her daughter is helping her to moderate a little, teensy bit and the last time I was with her she managed to avoid talking religion with me.
Her niece, OTH, has gone even further saying that her aunt, basically isn't holy enough. The niece moved to Phoenix and is completely immersing herself in the SSPX.