It should be possible to access the markets legally from within the US.

 "Who will win the 2024 US presidential election?", "Who will be POTUS on 2025/1/21?" and similar would count. 

https://eventtrader.interactivebrokers.com/en/home.php

ForecastEx went live a few months ago but hasn’t listed presidential election markets yet as of Sep 13, 2024.

https://www.wsj.com/livecoverage/stock-market-today-earnings-dow-sp500-nasdaq-live-08-01-2024/card/exclusive-prediction-market-goes-live-on-interactive-brokers-SqJ7SWnarkwSLOTJctWu

the market should be continuously available in the US for ≥1 week

 (not counting technical issues like a server outage)". (This will keep the same criteria as the Kalshi market).