It supports more devices than GrapheneOS i.e. nonpixels. That is where I would totally use it.
my Pixel 4a still gets GrapheneOS updates, so that is a tie.
GrapheneOS is great at security, privacy but also reliability and good detection and de-hardening mechanisms. Like, if I want I can disable most of it and even run full Google Apps.
DivestOS has sandboxed microG though, which sounds interesting. Would love to use UnifiedNLP, as an avid contributor to OpenCellID through "TowerCollector". I still just use A-GPS which sucks battery like hot chocolate. Like, 1h navigation and my device is empty.
Stock Android and iOS have location always enabled and still manage over a day battery life!
The real solution would be a UnifiedNLP app, running without user privileges. But that doesnt exist, and sounds a bit complex to me.