If I want to make all software programmable, I install Frida and easily hook into pretty much anything at the same privilege level.

Still, misleading headline aside, this sounds pretty cool as a reasonably well sandboxed plug-in architecture for software that chooses to use it.

Though if running in-process, it seems unlikely to be able to defend against hostile plugins that use e.g. speculative execution techniques to extract otherwise inaccessible data. But perhaps that's not the threat model here.