> Can you say more about the nav stack?

It's fine for robots like these

https://docs.nav2.org/about/robots.html

It's not useful for robots like these

https://www.youtube.com/watch?v=XoQI-kLRrXA

https://www.youtube.com/shorts/hKVwM5pa3NQ

https://www.youtube.com/shorts/XA_jjE2OES4

https://www.youtube.com/shorts/JOqc7dmmD5o

https://www.youtube.com/shorts/v9Pilgh1vcA