I have read this thread https://forum.xda-developers.com/galaxy-a8-2018/help/google-camera-galaxy-a8-2018-t3840838/page2 and in this post https://forum.xda-developers.com/showpost.php?p=77603383&postcount=170 there is this link https://drive.google.com/file/d/1eKlaHEyw97QcOe8_6pgVmmLs0ho31KrK/view with GCam_5.1.018.177470874.41362666__N6_1.8.apk
It`s working for both front and rear cameras (with active HDR too). I have tested literally every option including video and everything works ok and save correctly.
But for some reason even if full 24MP are selected in the settings I only get 8MP pictures which is really frustrating. I`ll continue my search for better working variant.
Here you can see some screenshots >
(I tried to attach them through the forum but didn`t work)
Nothing aside in the settings you can see in the screenshot in my earlier post.
The only thing I did may be differently before installation was to turn off the hdr in the build in camera app as per advise from somewhere. After that I went and turn it on and there were no problems at all. So now I have normally working samsung camera app and the gcam one. I can switch whatever I want in the apps and there are no problems.
I also have another camera app - CameraZoomFX (paid) with turned on Camera2 API and it also work ok with every available setting. I have even used them all at the same time to test what would happen - well nothing really. Everything works ok.