Are you sure about no HDMI out? Isn't that something that Android supports by default and since 1+6 will jave usb c I see no reason why it should not support?
No I'm afraid not, the last device to be able to use HDMI directly from usb-c was the HTC 10 to my recollection, since googles pixel doesn't use direct usb-c to HDMI, all devices are now the same.
Display link technology is a dock with its own chipset, meaning it can render for the device.
I have a thread in the one plus 5 forum because there simply was no way to use a wired solution, I've had the one plus since midnight on its launch day, the general idea was that HDMI out was not possible, I tested the display link devices I've got and it works.
You need an app but it works well.
Hopefully on the next batch of phones we can use HDMI directly, but I'd assume not.