Ok so I have to admit this is something I have always struggled with getting to work correctly even in BS3. But I want to have navbar links outside of the collapsed containe
The simplest way is using the flexbox utility classes, so no extra CSS is needed. Keep the items you always want to show out of the navbar-collapse div.
https://www.codeply.com/go/TWZGiy3VGw
Notice the use the responsive order-* classes to ensure the collapse menu items remain last (order-3) when in the collapsed/mobile breakpoint.