For you Greenlanders…
Do you wear your PFD under or over your Tuilik?
Which brand/model has a low-enough profile to wear under (e.g. Orbit Tour, Hybrid, etc.)
neither
most don’t wear pfd’s with tuiliks
Other options
Inlfatables. Vest, or maybe better the small belt type.
Both ways
If I am doing a normal day paddle along the coast, then I wear the PFD on the outside so I have access to stuff. If I am playing around or doing a short trip of a couple of hours, then I tend to wear a small WW style PFD inside. Some of the people I know who use tuiliks wear inflatables over the tuilik.
Inflatable belt…
…worn outside tuilik.
they’re called lifejackets now 
to me the real reason to wear one is the extra flotation for rolling. wearing a lifejacket/pfd in addition to the tuiliq inhibits certain types of rolls. It slows you down when moving underneath the boat, and when performing certain types of forward recovery rolls, especially hand rolls.
Keep in mind not advocating not wearing one, but I would say that over is better than under.
Both
I wear mine over when going for paddle and need access to stuff in the pockets or attached, like a camera or whistle. I wear it under when I am just rolling and messing around close to the put-in. I hit my head with the paddle once when I was learning a particular roll and thought that it could have potentially knocked me out, so I always wear a life jacket. I guess I am sort of a klutz, but I have also hit my head on a rock on the bottom while trying a roll. Now I wear the PFD and check the depth.