So, does it still depend on which device you have […] ?
it is device specific as decrypting drm protected content is implemented differently per device. Depending on distributor content is also encrypted differently, as in: to get 4K resolution video, you’ll need hardware assistance in decrypting, that might be only attainable (signed code… etc) with the vendor rom. My impression - most drm decryption has a fallback mode that can be done in software and my experience with those are positive.
Your friends S8: that one has a workaround that will stop trying the hw-assisted decrypt and force the less-assured but working software decrypt, see S8: Onleihe App Audiobooks do not work. Widevine is the same software that browsers use to decrypt and stream Netflix drm.