x264 has lossless compression methods and can also be 10bit.
AfterCodec has support for 10bit and YUV 4:4:4, not the lossless mode as far as i can see, but a high bitrate x264 should be better than the old simpler DCT based Prores or DNxHR at comparable bitrates
Now the question is if AE will import them correctly again.
Robert