I guess your best bet is to heavily debloat your original OS using adb or UniversalAndroidDebloaterNextGen for exemple and switch all apps from Google/Samsung/Partners to FOSS solution. Also tweak all the settings you can, ditch the PlayStore, Google account, etc...
I think that's the best you can do. Maybe in a few years you will have better option but I am not sure of that as it is a Samsung and it has become harder and harder in a few generations.
Here are some ressources. DYOR and use at your own risk :
https://github.com/Universal-Debloater-Alliance/universal-android-debloater-next-generation https://www.reddit.com/r/samsung/comments/rzhz13/ultimate_samsung_oneui_debloat_privacy/ https://github.com/invinciblevenom/debloat_samsung_android