Will dioxygen difluoride set fire to sand?
It is hard to be sure as it is too reactive to test
FOOF has been made, though no sane person would want to repeat the most recent synthesis (see the paywalled article reporting it) as it involves passing oxygen a fluorine through a red hot metal tube. An earlier paper that tested its reactivity stored it as a solid at 90K to stop it from, well, exploding. Derek Lowe, in his hilarious blog &quot;Things I Won't Work With&quot; describes some of the (very low temperature) reactions:

And he’s just getting warmed up, if that’s the right phrase to use for something that detonates things at -180C (that’s -300 Fahrenheit, if you only have a kitchen thermometer). The great majority of Streng’s reactions have surely never been run again. The paper goes on to react FOOF with everything else you wouldn’t react it with: ammonia (“vigorous”, this at 100K), water ice (explosion, natch), chlorine (“violent explosion”, so he added it more slowly the second time), red phosphorus (not good), bromine fluoride, chlorine trifluoride (say what?), perchloryl fluoride (!), tetrafluorohydrazine (how on Earth. . .), and on, and on. If the paper weren’t laid out in complete grammatical sentences and published in JACS, you’d swear it was the work of a violent lunatic. I ran out of vulgar expletives after the second page. A. G. Streng, folks, absolutely takes the corrosive exploding cake, and I have to tip my asbestos-lined titanium hat to him.

Many other reactivity experiments were not possible because they are just too impractical with something so dangerously explosive at temperatures any normal person might want to conduct reactions at (anything much above liquid nitrogen is bad for FOOF).
So, I suspect, we don't know whether it would set fire to sand as nobody has ever been able to make enough of it to test that reactivity, or, at least, test it and survive.
FOOF's–far more benign–relative chlorine trifluoride, which is commercially available and has several uses, most certainly does set sand on fire. As rocket scientists know. This account is from John D Clarke's Ignition:

It is hypergolic with every known fuel, and so rapidly hypergolic that no ignition delay has ever been measured. It is also hypergolic with such things as cloth, wood, and test engineers, not to mention asbestos, sand, and water—with which it reacts explosively.

So, given ClF3 is far less reactive than FOOF, it seems likely that FOOF, too, would set fire to sand. But with any luck we will never know for sure as nobody will be so monumentally, suicidally insane to try making enough of it to find out.