Thank you! I was just missing a few good search terms.
You should look into a MIPS helmet. It doesn’t fit too tightly on purpose. Rather, similar to the idea of airbags and crumple zones on cars, the MIPS liner is designed to provide some deceleration in the case of hitting your head.
I see they are recommending a rule change to require air vests x country.
Thankfully, they are “recommending” their use, not requiring them to be used.
I think they are sticking their collective neck out by even recommending their use. If someone is injured by an air vest, the FEI may find themselves in hot water.