The inflatable donut collars work well enough for areas on the upper body and sides. Very limited in scope though. Most dogs can still easily reach their paws, tail, hips/butt and belly with their teeth and tongue to lick at stitches in those areas and can paw at their face and ears to reach stitches/wounds on those areas. Basically not helpful for common issues like spay and neuter, cherry eye or corneal abrasion, torn toenails and such.
I have had more success with a clear plastic cone that the dog can see through but can't reach past.
We used one for Mesa after her spay. We were much happier with it than the cone. It made it difficult enough to reach the incisions so that she didn't bother them but it wasn't so large that she ran into things like she did with the regular cone. Mesa wasn't one of those dogs that HAD to get at her stitches, though. If your dog is more determined, it might not work for you.