Export PDF report from a specific set (or individual) of features

Question

I have a report layout (with child groups) and I want to export only the report of a specific set of features.

I tried to check if the fid matches with @atlas_featureid variable but I couldn't find any function to access this variable from the Python console.

How can I export only the reports for a specific set of features?

Edit: I've managed to "solve" the problem using the following workaround:

for feature in layer.getFeatures():
    report_index = feature.attribute('fid')
    QgsExpressionContextUtils.setProjectVariable(project, 'rik_report_index', report_index)
    filename = str(report_index) + '.pdf'
    result, error = QgsLayoutExporter.exportToPdf(report, project_dir + '/reports/' + filename, settings)

And I've wrote the formula @atlas_featureid != @rik_report_index on the following field:

But...

The time of the process increases exponentially.