If you want to publish a skill, you're almost certainly going to have provide assets of various kinds on public http locations. At the very least the T & C etc. have to be supplied as URLs but you may well want images to add to home cards and/or display directives.
The obvious place to put static assets, in this context, is CloudFront. Now in the kind of usage you'd expect Cloudfront prices, even if you don't get free tier, are pretty negligible. Here's my concern, AFAIK Amazon still doesn't have a cost cap. If you are so unfortunate as to sustain a DDOS attack on your cloudfront page the cost could be huge. I've read accounts of someone who was just setting up a small site for friends and family suddenly finding his monthly bill at $10,000.
Amazon can now give you cost notifications if your bill is starting to look silly, but even if you think to set one up, quite substantial amounts could mount up before you could reasonably work out what was going on and shut down your site. For the big guys the kind of monitoring to protect against this is do-able. For the independent developer, probably not.
Maybe you're away from your PC for a couple of weeks.
I've been on AWS for years, paying about 50p/month for various odds and ends. Wouldn't like to suddenly see a bill for thousands of pounds.
Now it's not a likely contingency, but neither is being struck by lightning, and yet we don't stand next to trees in a thunderstorm.
If I was expecting to make serious money out of skill writing the risk would be easier to justify. But I'm just doing it for fun, and potentially reputation.
So, how to mitigate? Have Amazon finally introduced a cost cap feature? If so I've yet to find it. How about setting the cost warning to an SNS topic, to which you attach a lambda which closes the distribution, or whatever resource might be exposed? Testing it would be an issue.