I also feel a bit guilty asking her to change her behaviour for him iykwim?
I totally get that, but you'd expect her to change her behaviour around eg. a newborn baby sibling, so a puppy is no different imo :)
I would try and make her feel like she's a really important part of the puppy's life - so for example, she could (under strict supervision) "help" you with things like training basics commands (sit, stay, roll over etc.), help you pick out things like toys for him, fill the dogs' food or water bowls etc.
So instead of expecting her to be quiet all the time, make looking after the puppy (within reason) something she can help with, and she can then learn how important it is that the puppy gets lots of sleep so it can grow big and strong etc.
Think I’m just concerned because he has been quite difficult recently with demand barking/excitable behaviour and seems a little better the last 2 days.
Remember, he's only little and a lot of that will be excitement and also just adolescence kicking it. He won't be a puppy forever!
I’d hate to think living with her is stressing him out because I don’t know what I’d do.
While many dogs do struggle with noisy DC, the reality is the vast majority will be absolutely fine once they're grown up, calmer and able to manage their emotions more, so please don't worry too much. The puppy/adolescent stage is the hardest part - it does get better, I promise!