Lets call things what they are - these IEMs have bad ergonomics, seriously bad. The body is big, the nozzle diameter is huge and IMHO the nozzle angle is not the best either. I have quite big ear canals, had many different IEMs over the years and typically use large size of ear tips, sometimes medium. I've never ever had issues with any IEMs not fitting inside my ear canals. But I remember that sometimes I needed to find another ear tips because the biggest bundled ones were not big enough. I find Etymotic ER4XR to be very comfortable. Now, with TRUTHEAR x Crinacle Zero I can get a decent seal with the small ear tips. Medium tips do seal a bit better for me but require a very careful slow insertion procedure (pulling up the ear + opening the mouth is mandatory), otherwise they start to cause pressure very soon. So, yeah, if you have ears and ear canals on a bigger side, you'll probably be fine, especially if you'll be lucky to match the angle of the nozzles. However, and here comes the educated guess, if you typically use small ear tips then you'll need a hammer to make these fit inside your ears. This is what it is, nothing to do with finicky ear canals, everything to do with the way they are made - they will not fit many people because of their shape and size, which is not great and too big in general. IMHO they might have improved the situation a lot have they made these huge nozzles moveable (like on VSonic GR07), so they at least can be adjusted to fit better, but they didn't, so we have, what we have.finicky ear canals
I do, however, like how they sound. Even though I do find them a bit shouty and lucking sub-bass, and prefer to EQ them a bit, I still think they are perfectly listenable without EQ and these are just nitpicks given their price. Unfortunately, due to their fit they may not work for many, which is a real pity and a lost opportunity.