People who use Brave use it for reasons other than access to a unique rendering engine. Many of those reasons apply to the iOS version as well.
Not making a case for Apple's decision here. I'd be happy if Gecko were available on iOS; there's no way I'd burn my battery like that, but competition is good.
But it's not as simple as "there's one browser on iOS" either, the rendering engine is just one part of what makes a browser unique and useful.
I think people are right not to trust Tencent with this kind of access.
iOS doesn't allow apps to read the user's phone number or scan local Wi-Fi access points. The only files sandboxed apps can read on iOS are ones created by the app, explicitly passed to the app, or made available by the user, which is also possible on the web.
The only thing mentioned that has the slightest bit of merit is being able to spam push notifications, and this is something that a) requires the user to grant permission, b) is easily disabled by the user if it's annoying, and c) explicitly forbidden by Apple:
> 4.5.3 Do not use Apple Services to spam, phish, or send unsolicited messages to customers, including Game Center, Push Notifications, etc. […]
> 4.5.4 Push Notifications must not be required for the app to function, and should not be used for advertising, promotions, or direct marketing purposes or to send sensitive personal or confidential information. Abuse of these services may result in revocation of your privileges.