Well apparently they have, just without advertising it! SoundAssistant lets you tweak the number of volume steps, set different volumes on a per-app basis, select apps that can play audio at the same time as other apps, and select apps to only play sound through headphones or when connected to Bluetooth. You can also enable a floating icon that appears for a set number of seconds when you press a volume button, that lets you adjust the equalizer directly without having to navigate through Settings.
Nothing earth shattering really, but if you're like me and have ultimately chosen to stay stock then this at least gives you some additional mods to play with.
Link to source at APKmirror: https://www.apkmirror.com/apk/samsun...load/download/