I am a very strong swimmer - to the point that I run rapids better OUT of my kayak than IN (I'm just a beginner-to-intermediate kayaker). But I never, never, never get in my kayak without my PFD.
For sure. I’ve even seen “instantly inflatable” life vests that have a small high pressure air can attached that can immediately give buoyancy, at the press of a button, without affecting comfort or balance before being activated.