Here is a simple method I use to share the same .bashrc / .zshrc / .bash_profile on multiple computers, while still retaining unique settings where I need them.

Suppose you want some special setting to apply only to your linux laptop, but not to your mac laptop.

$ mkdir ~/configs
$ touch ~/.is_linux

Next:

if [ -f '.is_linux' ]; then
    echo "This message only shows on my Linux laptops!"
fi

Now with different config files you can configure different environments from is single universal *rc file you keep in a dotfiles repo.

That’s it. It’s not fancy, but it works.