In my opinion there are very few trusted open-source BTC wallets and unfortunately there are almost no one for iOS. I mean I can’t trust most BTC wallets on the App Store for different reasons. Some of them were made by weird companies and others are not open-source.
Apart from Bluewallet which I believe is an open source bitcoin wallet on iOS, there is Bither, BitPay Wallet and Edge Wallet. Edge also supports other crypto assets besides bitcoin just like the Unstoppable wallet as we can see at
bitcoin.org.
Bluewallet is not yet available on the bitcoin.org site if we search, but bluewallet is a bitcoin wallet that can be trusted for use on iOS, including on Android.