We probably need a dedicated Edge thread, so here it is. To kick it off, Microsoft has just published a roadmap for Edge's PDF reader: Microsoft outlines what's next for the PDF reader in Edge - Neowin (Courtesy of NeoWin site)
And you have a weird problem with syncing collections from Edge on Android. Sometimes pages added to a collection won't show up in my Edge on Windows or iOS. Maybe it is a broken connection, but shouldn't it try again when a connection is re-established?