It looks like Filmic Pro will be first out of the gate to support Pro Res. The good news is that it will support Proxy, LT, regular 422, and HQ. This will certainly help with some of the storage constraint in 4k. I hadn't seen this talked about before and had hoped that support for the multiple flavors of Pro Res would happen.
Filmic Pro 6.17 brings ProRes video to iPhone 13 Pro - 9to5Mac
Filmic Pro adds ProRes video on iPhone for the very first time. Learn about the benefits of shooting ProRes on iPhone.
9to5mac.com