Just by chance, I got the idea to see if it would be possible to "import" live filters from Affinity Photo into Affinity Designer, and it worked perfectly! This is how I did it:
In Affinity Photo I created a shape and gave it a colour.
Then i applied one of the live filters, e.g. Depth of field.
Then I made this shape with the filter applied to it a group (although this is not necessary).
Then I copied this group and pasted it in an empty document in Affinity Designer.
It is now easy to manipulate this filter in Designer, by dubble klicking on the filter symbol in the layer view, just as in AP.
Lastly I selected the group in Designer and made it an asset, in the new asset category, Filters, that I created.
By repeating this procedure with other filters, you can get those live filters that you think might be useful, as a list of assets in Affinity Designer!
Of course if you have Affinity Publisher also, you can achieve this, and much more, in a more elegant way. I haven't checked whether you can import these assets into Designer without also owning Affinity Photo, but I guess it would be possible. If so, it would be a way of expanding the functionality of Affinity Designer as such!