Not sure if I'd use GrapheneOS even if it was available on other devices though. Really not a fan of the hostile attitude towards rooting when it's needed for basic functionality like backups — actual, reliable backups for every app, unlike those provided by the built-in solution.
If Samsung had allowed a non-stock OS to properly support devices like Samsung Galaxy Tab S10+ and Samsung Galaxy Tab S10 Ultra, we'd have been very interested. They did not allow it. They permanently cripple their devices if you unlock them. People should criticize Samsung for this rather than criticizing us for something we don't control. Companies like Fairphone are not realistically capable of building what we need due to lack of resources so there's little point in people bothering them about it.