How safe are ETFs if broad index funds didn’t exist?

Hi,

So the general rule for etf investing is to choose safe etf investing like a broad market index like sp500 or a total world index like $VT.

If a VT index or sp500 weren't available. What would you chose? Basically they are deemed be relatively low risk. Now if you wanted something risky with ETFS. Does that exist?

I have the basic total index and 50% other side in sp500 for “safe”. If I couldn't choose that, I'd go for something like Personally I'd for a mix of mid cap, small cap & QQQM.

That would probably yield more returns then a broad market but be more aggressive? Or something like a clean energy and ai etf bring more returns? Basically what would you choose for an Etf combo ( if you can't choose sp500 – or need to overlay with sp500)