Ask HN: How do you share your personal setup over different computers?

Hi! I'm an Ubuntu user and I love exploring all kinds of apps around the internet, specially FOSS. I install new software and update their configs very often, but upgrading my OS and sharing my setup over the two laptops I use is yet not very straightforward to me.

Do you also have to handle that? How do you do it? Is there any good software available out there to make it easy?