Special needs sleep training

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My 6m infant daughter is extremely aggressive with herself, always before bed and during night wakings; this has now extended to when she gets stressed during the day as well. She pulls clumps of her hair out, she scratches/rubs her face, eyes and ears so much she draws blood and leaves patches, and she whips her head side to side violently for long periods of time. She has very disordered sleep, sometimes taking many hours to fall asleep, sometimes waking every 30 mins, sometimes waking for 2-3 hours at a time multiple times a night. She always does the aggressive behaviors to try to fall asleep/back asleep, sometimes for hours at a time. She (and I) are incredibly sleep deprived. I am worried about her development, which is already delayed in many areas. I need her to sleep more and stop hurting herself. I have been getting many mixed recommendations: some say I should sleep train using the conventional "cry it out" method, others say if she's neurodivergent that would be cruel because she may not have the same self-soothing abilities and/or may have specific sensory needs. How can I get my baby much needed rest and replace her self-injurous behaviors with safer soothing techniques?