leafletmaps
Googlemaps shows you how large an area is on a map by showing a small bar with the number of miles/kilometers at the bottem left. Does leaflet also support this somehow?
I do not see it listed in the docs at leafletjs but it seems like something that the library should support.
I found that I could use SAFE FME to create the tiles. Since the LL84 wants a bounding box of (-90,-180;90,180) you have to add to the Y axis (row). But then it works fine. The formula is newY = 2**(zoomLevel-2) + oldY; (except for the exception for zoom levels 0 and 1).
Make sure you use the WebMapTiler with GoogleCRS84Quad (GoogleMapsCompatable would get you a spherical mercator, and we want LL84 (EPSG4326).
I am adding the screenshot for the FME project. I assume the same can be done with the gdal2tiles.py
GDAL can create vector tiles with the MVT driver https://gdal.org/drivers/vector/mvt.html
For converting GeoJSON data into vector tiles which are saved into MBTiles database file use a command like
ogr2ogr -f MVT -dsco FORMAT=MBTILES -dsco MAXZOOM=10 target.mbtiles source.geojson
Another option is to use Tippecanoe the https://github.com/mapbox/tippecanoe. GeoJSON is the only supported format as input but that is just what you have. For other formats you can convert source data first into GeoJSON with ogr2ogr. The Tippecanoe manual has examples about that as well.
Best Answer
I think you are looking for the scale bar. Use
L.control.scale().addTo(map);(ref. Leaflet documentation)