We actually use a combination of gadgets to track our baby's sleep and developmental progress. First of all, we use a baby movement tracker which has been super helpful for monitoring her sleep patterns. It gives us an idea of when she sleeps well and when she's still waking up too frequently. However, we've also found it really useful to supplement this with a smart baby scale that tracks her weight, body temperature, and more. This has helped us catch any potential health issues early on.
Lastly, I'd recommend downloading a pregnancy or parenting app , which offers additional insight into your baby's growth milestones and even has features such as personalized advice or recommendations from other parents in similar situations. For tracking sleep, we've found it useful to just write down her waking times and so forth in a basic journal. Maybe this is just me being old-school! Anyway, all of these have been super helpful for monitoring our baby's development, health, and sleep patterns, and the price has been really worth it to us.