So it turns out to open all sites in a collection, you need to tab the 3 dots next to the collection name and then choose "open all sites", which you then loose

So it turns out to open all sites in a collection, you need to tab the 3 dots next to the collection name and then choose "open all sites", which you then loose in your huge list of tabs that you had already opened to get to the "start page". Are the devs using this themselves even?