> Does anyone know if there exists any OPSEC procedure for me to use third party tools like this for my own concerning legal questions that is both ethical and allows me to be confident that my interactions won't land in discovery documents?

Isn't that a fundamental misunderstanding? Would "OPSEC" like that amount to destruction of evidence or contempt of court or something like that?

Like if all your incriminating documents are on some encrypted drive, it's not like that defeats discovery. You're supposed to decrypt them and hand them over.