I personally import my photos after each shoot to Lightroom Classic and sync the smart previews to cloud so that I can cull them on my phone or iPad.
I own both Android and iOS devices, on iOS version when a photo is rejected it will be greyed out in the library or in the thumbnails of the "Rate & review" mode. However I can't find this feature on the Android version.
I have checked every setting possible but still couldn't find it, pretty sure this is simply not a feature on Android version.
I find this very helpful and believe would benefit other Android users like me. Can you please add this feature to Android?