A small suitable treat may encourage voluntary investigation, but it should not be used to lure the cat into a space where they feel trapped or cannot exit comfortably. Place it where the cat can approach easily, and allow them to leave without being picked up or held in place. Eating a treat inside a bed does not prove that the bed is comfortable for sleeping. Continue to assess dimensions, surface and position independently. Keep any food allowance appropriate for your cat, and avoid leaving crumbs or perishable food in the bedding. Some cats respond better to a quiet familiar blanket or simply having the new item present. The goal is a relaxed introduction, not making the bed into a feeding station or repeatedly rewarding entry until the cat tolerates an otherwise unsuitable resting arrangement.
Place the first treat near an accessible edge rather than at the back of an unfamiliar cave. Remove any uneaten food afterwards so the bed remains a clean resting space.
For product comparisons alongside this advice, see Velvet Nest and Silver Velvet Nest. The details below explain their sizes and uses.
Further reading: cats.org.uk.
Velvet Nest
Silver Velvet Nest
AeroMat Chill Pad