[Speaking as ECC’s R&D Engineering manager]
ECC has been very clear that we do not intend to add major consensus features like ZSAs to zcashd. If some other organisation wants to do the development then they can, but they shouldn’t underestimate the amount of work required.
In any case, I strongly believe that it is not safe or feasible to rush ZSAs into NU6, if NU6 is to activate before the next halving expected in November. That is even if someone were to implement it in zcashd. The auditing required for the circuit changes alone is very substantial.
ZSAs in NU7 is ECC’s “Plan A”.