The output of this feature is exactly what our team is looking for (a single site with all modules/targets listed and searchable). However, we can't use the package plugin given it doesn't support building UIKit.
The original proposal thread Combined documentation of multiple targets - #24 by ronnqvist mentions the use of docc convert combined with merge.
I see that merge command was added to the docc subcommand, but I have yet to find any examples of how to use it, how it should be combined with other commands, the sequence of commands, and how it relates to what's being discussed here.
Essentially, is there a way to use this experimental feature outside of the swift package plugin or a way to accomplish the same output using docc and docbuild?
I posted a separate thread here in case it needs a deeper dive. Docbuild and Merge Multiple Docc Catalogs