Thanks for the feedback everyone. I think it will be useful to add a section on resource usage for each module in the module library documentation, so it's more intuitive to get a sense of how complex running circuits can be. Currently this is something that is visible at runtime while you're developing a circuit.
This is sort of analogous to how Axoloti keeps track of DSP load except that each running module on Zrna, like a gain stage or a lowpass filter section, etc. uses a discrete amount of hardware resources. An inverting gain stage uses a single opamp for example (1 out of the 8 available). There is no direct concept of DSP load because everything is happening in the analog domain. If you need more headroom for a more complicated design, you can simply chain the devices together.
My sense is that building a simple analog mastering device is well within the realm of possibility. It depends on how complex each part in the FX chain is.