The UnifiedPush server is intended to be a single source your phone can keep a persistent connection open to, rather than needing a connection per service/app (this is how Google’s Firebase notifications work too).
As Signal doesn’t support UnifiedPush, MollySocket keeps a permanent connection open to Signal’s servers to listen for new activity and forward them to your UnifiedPush server. This saves your phone keeping a permanent connection open to Signal’s servers and draining your mobile battery more.
I bought some gray imports a couple of months ago. Cost me about $100 more than Valve’s official AU prices, for the 1TB OLED.
My partner and I have been playing them both pretty much constantly since then. Very happy with them.