This can also be done by taking direction wheels and making them truly directional. Design the pattern so that as it rotates, it helps draw the air out from around the outside lip where the cooling vanes on the rotor push the hot air.Bring back Turbofans from the 80s aka BBS Turbofan covers for BBS RS/RFs, or OZs with the same covers.
They draw out hot air for brake cooling but also are smooth so that overall aero remains consistent.
It obviously wouldn't be as effective as purpose-built fans like you mentioned. But the small design tweaks would help reduce the high pressure area inside the wheel well. I'm working on a few designs now that are true directionals, but it'll be a while before they're done. I have one set done for my plaid (waiting for them to arrive now), but the directional design is just for aesthetics since it's an open spoke, and not for any type of additional cooling or pressure relief.