Hey there, Ryzen 3600 doesn't have integrated graphics, So it not an APU it's just a CPU. Only the 200GE, Ryzen - 3000G, 2200G, 2400G, 3200G and 3400G are APU's. You can still do CPU trans-coding and if your sticking to 1080P and under, on a single stream you'll be fine. Providing your dockers and VM's arnt hogging all your resources.
You will still need a video card at least for your initial UnRaid configuration and you will need a video card for your VM's unless you run them headless (don't quote me on that one) i think this might be based on your requirements for the VM.
Personally i went with a Ryzen 1600AF and i too had my concerns with AMD and UnRaid. But it looks like they have come along way. I haven't been plagued by any of the older issues that were present. Make sure you do your research with Ram speeds and Rank for motherboard and CPU compatibility. There a lot of good articles buried on here with helpful tips on these selections.
i went with a B450 chipset on my motherboard, if i had my pick again i would have gone for an x470 / x570 for extra Pci-e lanes. Again you'll need to check for CPU / EEC memory compatibility, speed rank etc.
**Edit** just to clarify, some motherboards Will require a GPU to boot with Ryzen CPU's - YMMV