ZKP is integrated in Google Wallet and has been running in production for a few months. We (Google) released the ZKP library as open source last year (this is the library used in production).
Afterwards, folks from ISRG produced an independent implementation
https://github.com/abetterinternet/zk-cred-longfellow with our blessing and occasional help. I don't know if the authors would call it "production ready" yet, but it is at least code complete, fast enough, and interoperable with ours.
Just writing here a line in defense of Rothko. His paintings are far harder to paint than it looks like. There were hundreds of layers, thinly applied, and carefully thought and with a developed technique. Try to paint that by yourself and you'll see.
I hope this fixes my issues with bluetooth on Linux. When I'm on battery the audio breaks all the time. I've tried all sorts of obscure config tweaks with Pulseaudio.