The Application Server is in progress, but it builds. The problem is that on x86, you can fall back on the BIOS w/ VESA to display video; while ARM lacks that functionality. If you can find/build a video driver it should Just Work(tm).
Err ... no? The problem with the ARM port is the lack of device drivers, and the fact that there is no userland/syscalls ABI set up yet at all. So there's still a lot to be done here.
You can see the current video drivers here:
https://github.com/haiku/haiku/blob/master/build/jam/images/...
Which are all x86/amd64-based. The RPi would actually be relatively simple to throw a framebuffer video driver together for, though:
* https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/s...
* https://github.com/raspberrypi/firmware/wiki
* https://github.com/dwelch67/raspberrypi/tree/master/video01