Here I found some info on the HTC USB C to 3.5mm adapter. The translation is not great, but it seems to imply that the adapter does have a DAC that converts 44.1k and 48k. A Dragonfly Black is capable of 96kHz.
The different Dragonfly models hat different output power (see the attached datasheet), so be careful that you chose a headphone that is reasonably sensitive and does not require a huge amount of power if you chose Dragonfly Black.
Just looking at the devices, it seems to me that the HTC adapter has less real estate available to house amplifier power, so I would suspect its output to be lower than that of the Dragonflies.
Given the right phone, the Dragonfly looks like an excellent choice at that price level. Reviews are generally positive. Maybe you can find some info in the reviews about particularly synergistic headphone pairings. I once had a Dragonfly 1.2 that I was very happy with (until the Mojo came along).