IO / Read and write KML file with geopandas and fiona driver

kml_io.py

import fiona 
import geopandas as gpd

# Enable fiona driver
gpd.io.file.fiona.drvsupport.supported_drivers['KML'] = 'rw'

# Read file
df = gpd.read_file(path, driver='KML')

# Write file
with fiona.drivers():
    # Might throw a WARNING - CPLE_NotSupported in b'dataset sample_out.kml does not support layer creation option ENCODING'
    df.to_file('sample_out.kml', driver='KML')
    
# Drop Z dimension of polygons that occurs often in kml 
import shapely
import fiona 
import geopandas as gpd

# Enable fiona driver
fiona.supported_drivers['KML'] = 'rw'

# Read file
df = gpd.read_file(path, driver='KML')

# Write file
with fiona.drivers():
    # Might throw a WARNING - CPLE_NotSupported in b'dataset sample_out.kml does not support layer creation option ENCODING'
    df.to_file('sample_out.kml', driver='KML') # You may change driver to GeoJSON

# Drop Z dimension of polygons that occurs often in kml - * expansion handles xy anx xyz cases
import shapely
df = df.set_geometry(
    df.geometry.map(
        lambda polygon: shapely.ops.transform(lambda x, y, *_: (x, y), polygon)
    )
)
# Orient the shape counter clockwise to be Vega conform
df = df.set_geometry(
    df.geometry.map(lambda geom: shapely.geometry.polygon.orient(geom))
)
    

I have really a few experiences with Linestring, sorry... It works fine on Polygon and Point type for me. The only constraint is that it does not work with nested KML as you could have in Google Earth.