XAUUSD trading for US citizen

Is it illegal for a US citizen to trade Xauusd with an off-shore broker?

If not, are there any overseas brokers which offer US citizens more then a 1:1 leverage for Xauusd?

Do not have the exact answer to your question, but you could also explore the option to open a company and trade via it Assuming that is legal for US citizens...
We are discussing about this option here ("Company Formation for the purpose of Trading..."):
https://www.metalsmine.com/showthread.php?t=953443

There was also a talk about "Broker for Trading XAU/USD for US citizens"
https://www.metalsmine.com/showthread.php?t=521235

I don't think it is illegal for US citizen's to trade CFDs, but it's illegal for brokers to allow you to trade them if that makes sense. Legitimate brokers won't allow US citizens to trade CFDs. Stay away from any overseas brokers offering US citizens to trade CFDs, they're not trustworthy.

I suggest trading GLD or IAU ETFs with a commission free broker like TD or IB. If you have a larger account, go for the micro gold futures contracts symbol MGC.