The good news is that using Leaflet Truesize plugin, you can add your own customized draggable polygons to the map. A map that I thought almost immediately is the representation of the draggable Brazilian states, so you could compare them to each other and to the size of other countries. And that is why this is used as an example for this tutorial.
So far, so good, but then you try to change the type of map between the available options (currently, OpenLayers, Leaflet and Mapbox GL JS) QGIS freezes and you have to close the application via Windows Task Manager. I observed the occurrence on QGIS 3.20 Odense and on QGIS 3.16 Hannover, version of qgis2web 3.16.