Capsicum is dead outside of FreeBSD, the Linux port went nowhere, and in the handful of places where it is used in FreeBSD base, it's not even utilizing capabilities to its full potential. It wasn't even enabled by default for many years, until 11 or 12?

Meanwhile pledge(2) is protecting a large percentage of the OpenBSD base system, something like 85/90% of all programs. And unlike Capsicum, it is "practical" for developers. And important ports like archivers, and web browsers. The Capsicum project never shipped the much touted Capsicum-ized chrome, but OpenBSD has pledge/unveil chrome packages by default.