QGis Merge Equally-named and Grouped Layers

inspired by https://gis.stackexchange.com/a/361296

import processing

grouped_layers_by_name = {}
distinct_layer_names = set()

project_layers = []

for l in QgsProject.instance().layerTreeRoot().children():
	project_layers += l.children()

for layer_item in project_layers:
    layer_name = layer_item.name()
    distinct_layer_names.add(layer_name)
    grouped_layers_by_name[layer_name] = QgsProject.instance().mapLayersByName(layer_name)

print('Total number of distinct layers: ' + str(len(distinct_layer_names)))

for layer_name in distinct_layer_names:
    print('Processing layer: ' + layer_name + '...', end=' ')
    merged_layer_file_name = './5000/' + layer_name + '.gpkg'
    ls = grouped_layers_by_name.get(layer_name)
    if ls is None:
        continue
    print(ls)
    alg_params = {'LAYERS': ls, 'OUTPUT': merged_layer_file_name}
    result = processing.run('native:mergevectorlayers', alg_params)
    print(' done.')

print('All layers have been merged.')