import bpy
from collections import Counter
print('types',Counter(o.type for o in bpy.data.objects))
print('collections',[(c.name,len(c.objects)) for c in bpy.data.collections])
print('cameras',[(o.name,o.type) for o in bpy.data.objects if o.type=='CAMERA'])
print('unlinked',[(o.name,o.type) for o in bpy.data.objects if not o.users_collection])
result={'types':dict(Counter(o.type for o in bpy.data.objects)),'collections':[(c.name,len(c.objects)) for c in bpy.data.collections],'camera':bpy.context.scene.camera.name}


types Counter({'MESH': 85, 'LIGHT': 5, 'CAMERA': 1})
collections [('BUST • FORM', 8), ('Collection', 0), ('FACE • SCULPTED PLANES', 41), ('HAIR • CLUMPED CURLS', 29), ('PEDESTAL', 6), ('STUDIO • LIGHT & BACKDROP', 7)]
cameras [('Catalogue camera • 3/4 eye level', 'CAMERA')]
unlinked []