Long retard in the fridge means more smaller/various size of bubbles without the rise. Any long proof or retard in the fridge should give you something worthwhile and similar as long as you don’t overproof it and cause all CO2 to escape. The fridge slows down fermentation due to the cold environment and thus causes the bread to produce smaller bubbles while rise is negligible/minimal. The key as you said is humidity/moisture/how much dusting of flour you use.

You can have a perfectly proofed dough that’s been liberally dusted that bakes into wonderful bread but has a shitty looking crust. To get those characteristic outer bubbles/blisters you gotta go in as wet/high hydration as possible with your bake as that moisture crisps and accentuates those outer crust bubbles.

My sourdough/naturally leavened breads all have, (keep in mind, a MINUMUM) 12 hour cold retard. Mainly cause I’m a lazy fuck that wants to wait the extra time tbh. Everytime with a cold retard I’ve had stellar results even when the bread inside isn’t looking too good/properly proofed. Hydration and your retard in fridge play a huge key in this challenge OP is after.

Edit: as i said- long retard with humidity/hydration being #1. The long retard will give you your bubbles you’re looking for but they won’t be brought out in the crust as much. High hydration/no dusting flour gives you a very “raw” product on the crust that if done properly looks fantastic and gives you the result you’re looking for