"Installing new modules on an existing Cardinal binary is not possible at run-time, but we can add new modules to the build."[1]

From the original release — being able to select 3rd-party plugins a la carte is probably Rack's most important feature, both for users and developers. Apparently there's a technical reason: "Cardinal is intentionally a fully self-contained plugin, Whatever is contained in the current build is what you can use"[2], but it seems like Rack Pro makes it work so I'm not sure why that's the case.

[1]https://kx.studio/News/?action=view&url=cardinal-2202-is-now... [2]https://github.com/DISTRHO/Cardinal/blob/main/docs/FAQ.md