Was a while since I tried this but it should work.
What steps have you taken and what is the current state?
What GPU:s do you have and ESX/Horizon versions?
I've tried with ESXi 5.5U3b + Horizon View 5.3 and ESXi 6.0U2 + Horizon View 6.2 and i couldn't make it work.
When i connect with view client and i run dxdiag it shows the VMware SVGA card, and if i disable the VMware SVGA device it show "n/a".
VM: Win7 64bits, 4vCPUs, 4GB RAM.
VM Advanced settings:
pciHole.start = "1200"
pciHole.end = "2200"
Memory all reserved.
NVIDIA GTX480 soft modded into one Quadro 6000
ATI Radeon HD 7800
MB: Asrock Rack EPC602D8A
CPU: Intel(R) Core(TM) i7-3820 CPU @ 3.60GHz
RAM: 20GB - 2 x 4GB DDR3 PC3-10600 (Kingston 99U5471-020.A00LF) + 2 x 8GB DDR3 PC3-10600 (Kingston 99U5471-052.A00LF)
RAID CARD: LSI MegaRaid 8888ELP
I followed the vmware-horizon-view-graphics-acceleration-deployment.pdf.
1 - Installed Windows 7 / Reboot
2 - Install VMware Tools / Reboot
3 - Added PCI device to VM
4 - Install NVIDIA / AMD drivers / Reboot
5 - Install view agent / Reboot
6 - MontereyEnable.exe -enable (on case of NVIDIA card) / Reboot
NOTE1: I add to change /etc/vmware/passthru.map because when i started the VM that add the graphics card in passthrough the ESXi hangs.
I add to change the existing entrance for NVIDIA devices from bridge to link and also add a similar line for my ATI card:
1002 6818 link false
1002 aab0 link false
10de ffff link false
NOTE2: both cards are working well, if i connect a monitor to the cards and add a mouse and keyboard to the VM it works fine.
For Horizon View pool settings i followed this article:
4. When configuring the virtual machine for vDGA, it was really not clear on how to configure the VM and what pool settings to use for graphics acceleration. The pool needs to be set on “Use vSphere Settings” on the pool.
VM Settings (Video Card):
6. You must edit these settings using the web client:
Make sure the video card is set to:
1. Software Acceleration
2. 3D Acceleration is UNCHECKED
Oh, its a home project... I thought you where building a proper supported solution.
Then I can't help out, I'm just working with enterprise-grade stuff, but good luck!