> Today the options are either free and open source (which can be extremely high quality, like Jolt: https://github.com/jrouwe/JoltPhysics)

I did mention this was changing in particular with physics engines. That being said, proprietary dependencies still reign supreme in places like audio engines. Something like OpenAL isn't really a replacement for FMOD or Wwise. I know those off-the-shelf engines roll their own replacements, but then they also roll their own pathfinding and navmesh generation as far as I know.