Is Librem phone 5 born to be compatible with Android software packages? If no are there ways installing Replicant system for Librem phone 5 that liberates nonfree Android?
The operating that ships on the Librem 5 will not be able to run Android packages out of the box. Currently GNU/Linux support for Android packages is a work-in-progress. Anbox is a project for such support and may one day be a viable option.
As far as replicant support for the Librem 5 goes, read this thread on the Replicant forum.
At the end of the day, the Librem 5 will support any operating system we port to it and I believe it will be a great target for Android Open Source Project forks.
Especially now that the linux graphic stack and the android graphic stack have common bridge i assume that someone for sure will do it.