the raspberry pi3 gets with amazon vod add-on and libreelec 11.06 480p;
i suppose this will be the case also for raspberry pi4 or 5, if one wants to use Kodi/Libreleec instead of Android.
from the FAQ on Sandmann79/xmbc Wiki
QuoteHow can I play movies in HD/UHD?
4K/HD playback is only possible with a Widevine L1 secured device (mostly Android, e.g. Shield, MiBox), all other devices are limited to SD resolution. For 4K playback as well as for the Android data source, the device has to be registered once at Amazon. For this, the login has to be performed again.
On Android you can enable the use android app for 4K videos at settings. This starts the video in the official prime video app and works only for videos with "UHD", "Ultra HD" or "4K" in the video title.