Cloud here means something specific: there is no machine of yours in the loop. No signage server in a back office, no VPN to reach a store, nobody patching anything on a Sunday.
Your screens, your devices, your content, your data, and the right to export all of it. Cloud is a choice about who runs the plumbing, not about who owns the water.
A network across more than one address is where self hosting starts to hurt. Every extra location adds a device that has to reach your server, a firewall rule, a certificate and a person who knows about it. Cloud keeps the count of things you maintain flat while the count of screens grows.
A single room with one screen and an in house sysadmin can reasonably run open source. If that describes you, that is a fine answer, and this page will not pretend otherwise. The moment there is a second address, the calculation changes.
The screen keeps playing. The player holds its schedule and its media locally, so an outage at our end, or at your store's end, does not blank a wall. When the connection returns, the player applies changes and uploads the play records it collected in the meantime.
That is the shape of the reliability question worth asking any vendor: not whether the platform can go down, but what the wall shows while it is.
The security page goes through all of this properly.
One screen, one playlist, one week of play records. That is the whole evaluation, and it does not need a server.