My 10 week old is doing the same
the hand in mouth is a totally normal developmental process! it’s usually baby learning how to self soothe, sometimes can mean teething but without other symptoms i’d guess it’s just that :)
Mines 8 weeks tomorrow and exactly the same! Really didnt want to use a dummy but she just wanted something in her mouth all the time so was making herself sick having too much milk! Otherwise its hands or my shoulder or anything near her mouth!
It’s a really normal developmental process they are essentially finding there hands it’s all to do with motor skills and touch, you should encourage it my HV said my little one has never taken a dummy has only just started with the hands in mouth and is apparently really normal round the 8 week mark
Following, my LO’s 8 weeks too and exactly the same, spits his dummy out to put his hand in his mouth