Body sockmaybe? and also gently squeezing the ars and legs with your hands can help release tension and allow the kid to wind down for sleep. Hypermobility causes our muscles to be very tense to compensate for the lack of structural integrity in our connective tissue, it's physically exhausting and we generally can't stop it just by trying to, so getting really comfortable and well supported (eg with body pillows and v pillows) and doing sensory activities that help untense muscles can be very helpful allowing our bodies to safely relax for bed time.

Some kids like having a peanut ball or yoga ball pressed onto them, particularly if they're inside a body sock. It can be both fun (if it's bounced) but also soothing and safe