Save / Load with multiple data inputs / outputs

I'm frequently dealing with a really weird tabular data structure called a PCL file - basically, the first n rows contain various forms of metadata (first column for these rows is metadata name), then below that it has a sample x feature matrix. So for example, I might have my_data.pcl:

Since most of the operations occur on the numerical table part, and storing this all in a single dataframe (or whatever) would generally lead to columns with type Any, what I'd like to be able to do is have load/save functions that make/take two iterable tables, that share the sampleID row, eg the two tables would be:

metadatadf:

featuredf:

And I'd like to be able to do something like:

(x, y) = load("my_data.pcl", id_row="sampleID")
metadatadf = DataFrame(x)
featuredf = DataFrame(y)

save("new_table.pcl", metadatadf, featuredf)

Can I get some guidance on whether this is possible / makes sense to use the FileIO framework for this?

Review FileIO's load/save interface against the proposed two-table PCL examples and the id_row="sampleID" option. Determine whether multi-input/output dispatch and this metadata/feature split fit the framework, then document a concrete API decision and its expected behavior.