We are very cautious with Apple as we suffered from them before [1]. So we're trying to stick to the APIs they provide. I hope the new URL filtering API [2] will improve the situation with the system-wide filtering, but our request for API access is still being reviewed by Apple.
Regarding jailbroken iOS devices, unlike Android the numbers are really marginal so it won't be feasible to support them.
[1]: https://adguard.com/en/blog/adguard-pro-discontinued.html
[2]: https://adguard.com/en/blog/apple-url-filter-system-wide-fil...