Here to say I'm having a similar issues with my 6700XT. I can only use my Intel iGPU to install Zorin while my 6700XT isn't able to be used. I've tried to boot with only a monitor connected to the AMD GPU, but get "IGC 0000:05:00.0 no suspend buffer for PTM" error on the GRUB and unable to boot. I tried updating the drivers with AMDGPUPRO, but that ruined my installation and had to reinstall entirely. Here are the terminal read outs
00:02.0 VGA compatible controller: Intel Corporation CometLake-S GT2 [UHD Graphics 630] (rev 05)
DeviceName: Onboard - Video
Subsystem: ASUSTeK Computer Inc. Device 8694
Kernel driver in use: i915
03:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Navi 22 [Radeon RX 6700/6700 XT / 6800M] (rev c1)
Subsystem: Advanced Micro Devices, Inc. [AMD/ATI] Device 0e36
Kernel modules: amdgpu
03:00.1 Audio device: Advanced Micro Devices, Inc. [AMD/ATI] Navi 21 HDMI Audio [Radeon RX 6800/6800 XT / 6900 XT]
[11:31 AM]
ronin@ronin:~$ xrandr --listproviders
Providers: number : 1
Provider 0: id: 0x45 cap: 0x9, Source Output, Sink Offload crtcs: 3 outputs: 3 associated providers: 0 name:modesetting
IT does seem that my AMD card is detecting, but it isn't capable of being use as a provider? I'm a bit new to linux here hence the reason I went with Zorin, but I'm really stumped on this one