If you have a NVMe disk that happens to let's say report inaccurate capabilities (i.e. lie cause it was built cheap), the NVMe driver in DragonFly can now attempt to survive the surprise.
DragonFly and Hyper-V's virtual disk support do not appear to co-operate well, according to this bug report.  Anyone have a Hyper-V host where they can confirm?
ndis(4) is removed from DragonFly; it's probably been years since it was applicable to any hardware.  I don't think it will affect anyone - but it's an interesting tool from a historical perspective; for a while it was possible to use Windows XP drivers to create a BSD network driver, effectively.
If you have an AR9485 wireless adapter, this bug report notes the appropriate config for DragonFly.  Might work for other hardware too?
I've seen this a number of times over the years: if you're installing DragonFly and the install drive seems to disappear, it might be the USB port you plug into.
Sascha Wildner has added the PCI IDs for various recent ichsmb(4) devices.  This I think just means a correct device name in dmesg, but unidentified smbus devices has plagued me for years, even with other operating systems.