I'm curious about this too. AFAIK the most recent leaked Cellebrite docs indicated that GOS can't be broken into, and I dunno how iOS could be more secure than that.
It depends what you mean by secure. Vulnerabilities is a market and if GOS happens to secure the vulnerabilities that are convenient and work on all standard Android releases, most of the market doesn't support putting the research into setting up additional vulnerabilities against it as they will until another iOS vulnerability is found and weaponized.