@Glitchymn1 You mention my name and I appear! 😁
@LaBelleSauvage123 - it completely depends on what sort of dog you want. Some dogs breeds are just better with other pets. For example, you'd be a bit bonkers to get a sighthound, raise it, and then get kittens. But, if you got something like a Lab (as you mention) or a Poodle etc then you're more likely to have success either way, I imagine.
What I would say though is raising even one puppy is a full time job and raising any sort of retriever (Lab, Goldie, Flattie) is a thankless task and you will probably regret it at least once. Adding kittens to that would be insane.
I don't think it's any better or any worse for their relations if you get them at the same time - but what I do know is not many responsible breeders would sell a puppy to you if you said you planned to get kittens shortly after or had just gotten kittens. Just as they wouldn't sell to you if you already had a v. young puppy at home.
You might find the odd one - if you're very very lucky - but they'll be few and far between. That is simply because although people have best intentions...best intentions aren't enough. And, of course, buying a puppy from the type of slightly irresponsible breeder will come with it's own challenges, so you need to consider it carefully.
That's not to say don't do it, but you just need to be aware this is bigger than 'which way around do I do it.'