You might be interested in this blog post, which _does_ use a scoring rule: http://zackmdavis.net/blog/2020/11/scoring-2020-us-president....
I guess between this and the other commenter who made money betting 538's model on predictit, I consider this pretty thoroughly debunked.
I saw some sports betting sites were offering odds, but not really a true market like predictit I think
In order to interpret the polls, you need top statisticians with lots of domain knowledge. In order to interpret the betting market, you simply read the odds and are done.
The particular market available to US residents has separate issues about "reading the odds" where events that strictly contain other events are often priced multiple pennies cheaper, the total number of expected presidents is often ~1.1, events with probability at least 0.9 are almost always underpriced, often by a nickel or more, etc.