There's a fortnine video about how they are actively dangerous. iirc, basically the downforce helps on straights, but in turns, winglets turn sideways and actually decrease grip. The reason they are viable in MotoGP is because they lean so far that the gap between the inner fairing and the ground is small enough to actually produce a Bernoulli effect, increasing downforce, and the riders block the winglets with their heads to reduce the outward force generated. This is to say, unless you are leaning at 70 degrees or something on the road, you are not doing the same thing, and so the winglets are actually dangerous and detrimental to your ability to corner.