Yea, someone probably should. Probably one of the hardware wallet vendors who are complaining that there’s no standard and that’s why they never bothered to implement it (nevermind that it’s implemented in secp256k1-zkp and can be done at the HWI driver layer, but indeed it’s be better as a PSBT field). 

 Sadly no implementation exists for Taproot AFAIK, but the BitBox folks have a PR to secp256k1-zkp at least.