I concur that we do not yet know how widespread it is in high schools and elementary schools. What we do know, however, are these three things: these policies are rampant on the collegiate level; that the extreme Left controls the halls of academia almost completely at this point, at least in America and Canada, and I know they have made strong encroachments into Britain; and that we see good evidence of at least the beginnings of these things leaking down into the high school and elementary levels.
Hence, there is a legit concern against those who oppose "wokeness" that if it's not yet rampant on the first and secondary levels of education, it is likely headed in that direction. If it's not yet rampant, that does not mean, IMO, that there is no cause for concern, as I do think it needs to be nipped in the bud, so to speak, before it gets to that point.
It also creates another issue to contend with that is rather dire. Especially in the American South, the SJW infiltration of academia and the entertainment industry etc. are causing a severe backlash from extreme elements of the Right. They are fighting back in negative ways from the standpoint of their own set of bigoted identity politics, by trying to label any classic work that has positive or scientifically defensive positions for equality of blacks and homosexuals etc, or any critique of Western society, as "woke." This is pushing the rest of us between two authoritarian forces that are both motivated by bigotry, hatred, and censorship, albeit the flip side of each other.
This is why it's very, very important for people on the Classic Left to get over their fear of the SJWs en masse and fight both of these extremist elements, and to join with reasonable Libertarians and civil libertarian people on the moderate Right to do this.