The OP is trying to set up AWS IoT. That should be in scope. Short reason: It's right there in the name.
Also on-topic are any coding questions which have an IoT purpose. Stack Exchange gave us a site to help out people who want to create or use IoT stuff. Something along our definition of IoT devices (the result was quite fuzzy) and our discussed tag lines should set the borders.
Q&A for builders and users of networked sensors and control devices—be it for your smart home, industry automation or environmental sensors.
One of the guiding principles around all new beta sites is that a question being on-topic somewhere else doesn't mean necessarily that it is off-topic on a new site. With the logic that there are more coders on SO (which is very true) no other site in the network should allow any coding questions. Obviously that's not the case when one considers the almost 1800 Java questions on Superuser. On the other hand developer-only focused sites do not survive the Area 51 process as duplicate of Stack Overflow.
So yes, our SE mandate if you will does not point to pure coding questions being on-topic but coding questions can very well be on-topic on other sites on the network.
Are there more people on SO who know about AWS-IoT. Considering the user base in the millions—probably. Are IoT questions getting good answers over there? At the time of this writing there are 302 questions tagged AWS-IoT and 172 of those unanswered (i.e. no upvoted answer). That's a meager 43% success rate—well below Stack Overflows 71% answer rate. Other IoT-related tags rank similarly. Our 24 AWS-IoT questions however have only 2 unanswered with one of the latter asked yesterday. That's well over 90% if one calls that statistically significant.
Stack Exchange gave us a site to create out a place in the network for IoT questions. We're not here to duplicate Stack Overflow, but if someone tries to set up their future IoT solution and the solution happens to require some coding or the configuration needs some tweaks it's very much on-topic.
If it's about basic coding problems like basic string operations point the people to Stack Overflow, if it's more specific, especially with an expressed IoT purpose welcome them.