LOs often wake up 45 mins into their nap because that's how long one of their sleep cycles is, so you're doing the right thing allowing him a chance to self settle rather than rushing in straight away. They tend to need more than 45 mins each nap, so it's good if he can get back to sleep if possible. If he's not crying there's no need to "rescue" him, but if he's not settled after a while it might be a good idea to check if anything is keeping him awake, such as a dirty nappy. If he's cranky he might need a bit of help still at this age to resettle so if you want to give him the dummy that's absolutely fine IMO. Sucking is a form of self soothing for them and he's obviously too young to put it in himself. Noise is also popular at this age, so hairdryer is a good idea
A shame i doesn't work when they're older, I always end up waking my LO with the hairdryer
