I mentioned GDAL in case it is of use, as it covers a huge number of formats (and thus has a correspondingly large code base). You might be able to glean something from its source code for the OSM driver.

A quick download of one feature type might be possible, but to be honest I've never tried either a full or partial download of these data (hence my answer did not have any code examples). If you do download all features for a region then you should not need to set up a database, though, as you can access the contents of the file directly using Geo::GDAL::FFI::Dataset and Geo::GDAL::FFI::Layer methods, including running SQL queries over the data (see ExecuteSQL in the Geo::GDAL::Dataset::Dataset docs). The Synopsis for Geo::GDAL::FFI has an example of how to load the data, copied below.

I would definitely be interested in seeing something implemented in Perl to access these data, and can help with testing if you need it.

#  from the Geo::GDAL::FFI synopsis,
#  it should detect the file type automatically (untested)

use Geo::GDAL::FFI qw/Open/;
 
my $layer = Open('test.shp')->GetLayer;
$layer->ResetReading;
while (my $feature = $layer->GetNextFeature) {
    my $value = $feature->GetField('name');
    my $geom  = $feature->GetGeomField;
    say $value, ' ', $geom->AsText;
}
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