How to subscribe to all games news feeds efficiently

[magne4000]

I would like to subscribe to new published announcements for every Steam games, but in the manner of SteamApps.PICSChangesCallback (i.e. having Steam Network push them to me instead of pulling the data).

Currently I only found 2 ways:

• Call SteamAPI or RSS endpoint every now and then: This works, but it doesn't scale well for the entirety of Steam games (several tens of thousands endpoints to call frequently)
• Wait for SteamApps.PICSChangesCallback, get the appid and call one of the above endpoint to check if there is a news: Scales a lot better, but I could easily miss some updates (updates posted after the package is published to Steam for instance)