Is there a Polymarket API for events and markets?

Yes. Social Fetch has 42 Polymarket routes under /v1/polymarket: events, event lookup, insights, annotations, comments, markets, market lookup by id, slug or condition id, batch market lookup, order books, prices, price history, trades, holders, tags, series, sports, teams, search, movers, user profiles, positions, activity, stats, PnL, leaderboards, biggest wins, Perps and Polymarket US. Authenticate with your Social Fetch API key in x-api-key.