In the PowerApps community, from time to time a question is asked about how to exceed the item limit (500 by default, minimum 1 and maximum 2000) for a SharePoint list.
When I see this, I often wonder if that person really wants their fellow employees to scroll for hundreds of items in a gallery? I personally don't and prefer creating a solution with filtering, sorting and if possible searching.
But is it possible? Yes, it is possible to scroll through all items from a SharePoint list in a gallery. What you need to know is that you:
must add the data source directly to the gallery.
can only use functions which are delegable for that data source.
With these restrictions, even a formula like
SortByColumns(Filter('SPList', Status = "Open"), "Modified", Descending)
will show all items.
What has been "said" above also counts for other data sources like SQL Server and the Common Data Service. With SQL Server even more functions are possible.