Is this an item lying in the world that we could take right now? It's valid, it isn't in an inventory, it doesn't refuse us (Sandbox.BaseInventoryItem.OnCanPickup(Sandbox.InventoryComponent)), and it isn't something we dropped a moment ago. Runs on the host for routed pickup requests, making it the place to validate them - the base deliberately has no range check (like shot claims, what's plausible is game policy), so override to add range or line-of-sight rules.