It’s going to be weaker in caffeine content but still stronger tasting. This is ideal if you are trying to reduce daily caffeine intake or just like the taste of strong coffee.
Some people still need a kick of espresso but don’t want/need 3 shots worth in a single drink.
I don’t really have a stake in this race because it’s quite a dilemma (personally I like the idea of Graphene supporting more devices with varying security promises) but I’d imagine between buying a 2nd hand Pixel or exclusively using Google services, Google would rather people do the latter.
They simply make more out of data gathering and GrapheneOS sidessteps that, so as a user I’m leaning towards the former so I can more readily degoogle myself.