Hello,
I want to install the Haiku OS because as I read about it, it is a new OS and not based on Linux or…, but is it possible to install GNU/Linux application under it?
Any guidance to migrate a GNU/Linux application to Haiku OS? For example, migration the VirtualBox to Haiku OS.
Thank you.
Haiku is not binary compatible with Linux or FreeBSD, you need to recompile program to run it on Haiku.
VirtualBox is not ported to Haiku yet, bu you can use Qemu instead. You can install Qemu with pkgman install qemu.
Hello. No, you can’t install Linux apps under Haiku. Haiku doesn’t provide binary compatibility with Linux or Windows.
However, as a POSIX system, you can port software from Linux, assuming that the libraries that are needed are available also in Haiku. For example, a wide selection of Qt apps had been ported to Haiku.
How can I port an application? Any guidance about it?
Download the source code and compile?
Download the source code, patch and compile 
Before you start porting an application please check if it is already available in HaikuDepot or via haikuports (the link has already been posted)
If it is not available already I would start by checking what prerequisites the app has, e.g. which language it is written in, on which libraries it depends, and if it is a GUI application the most important thing is the GUI toolkit it uses. QT is already available under Haiku, GTK isn’t (apart from a few experiments). After checking that you just start compiling the app and dealing one by one with the errors that are likely to occur.
You can ask for help here, or on the haiku IRC channel where most of the developers and software porters are around.
Anyway, have fun and don’t hesitate to ask for help 