Only in the EU. Highlighting that that the only reason they’ve changed their mind is because of regulatory pressure. Android allowed alternative engines on day one, iOS allows it, what, 17 years after launch? It’s still fair to criticise Apple for the time it took and the extra lengths they’ve gone to in order to only allow it where they’ve been forced.
No other iOS browser engines have been approved, or even exist at this point. Probably won't see any real alternative browsers in the EU until they finish the rumored WebBrowserKit or whatever, to help contain JIT services.