I just have the same issue. I need it for a0 sewing patterns. At the moment i have to safe every page in a single file or the size layers has to be deselct for every page. With a4 pages i dont even think about it with affinity. Hope there will be a solution for this.
And i hope there will be a simple solution for insert a grid. At the moment i make it in inkscape and transfer it to affinity.
Im lokking forward to it.
Greetings