The usual covenant debate on Bitcoin starts with Script and soft forks. PIPEs v2 starts somewhere stranger: it asks whether a spend condition can be enforced by making the signing key itself unavailable until a proof exists. That move shifts the burden away from on-chain verification and into witness encryption, committee setup, a huge off-chain artifact, and the engineering needed to bind them together.
The result is one of the most interesting proposals in current Bitcoin research because it enlarges the design space without asking Bitcoin consensus to change.