Small-to-medium Mirrorless Camera (e.g. Fujifilm X-T4, Sony A7IV, Canon RP, Nikon Z7 II etc) with small lens attached and two small spare lenses.
Small-to-medium Canon DSLR on it's side with lens attached (e.g. Canon 5D MkIV or Canon 6D MkII with 24-70mm f2.8 lens) plus a spare small-to-medium lens. Maybe a 3rd lens too depending on size.
Two Leica M cameras on their side with lenses attached, possibly a spare lens too.
Small foldable drones such as Mavid Air 2 or Mavic Mini 2 with space to spare.