I know you can rename an object by selecting it on the layer panel and then double-clicking on its name.
The problem is that if you have a large document with thousands of objects you first need to select the object you want to rename on the document and then spend a looooot of time locating the highlighted item on the layer panel so that you can double-click on its name in order to change it.
This should be a lot easier.
You just need to add a "rename object" option on the layer menu (and/or the context menu you get for the selected object).
We use Affinity Designer to create graphics we then export as SVG files. The name of each object in SVG files is usually VERY IMPORTANT so that you can work with them on web applications.
Naming objects should be a lot easier when you have multiple objects on the document.
Another way to fix this situation would be that whenever you select a SINGLE object on the document, the layer panel would automatically scroll to that object on the list to make it visible to you (instead of you having to manually look for it on the list, which is a pain if you have hundreds of objects).
Once the object has been located for you on the layer panel, you can easily proceed to rename it by double-clicking on its name.