A fallen object has five units of strength, and the fire eats them in a couple of moments: a common thing in lava disappears before you can pull it out. Each tick object in lava rises slightly up, so a non-flammable non-crowd takes it to the surface — it can be caught.
Items in a player's inventory do not burn from lava: if a player dies in lava, everything that fell from him, except netherite, will burn.