This is not a fully formed solution, and it is very dependant upon how Laserfiche has structured the LFForms database (and thus I can't promise it won't be changed in a future version).

This is based on Forms Version 11.0.2212.30987 (Version 11 Update 3).

In the LFForms database, there is a view named worker_instance_data.  If you search for the Forms instance ID on that view, example: 

SELECT *
FROM [LFForms].[dbo].[worker_instance_data]
WHERE [bp_instance_id] = 123456

One of the values you get back is a UUID in a column named resume_id.

You can use that resume_id UUID to create a URL that mimics the URLs that are automatically included in Task Assignment emails.

https://YOURFORMSURL/forms/form/approval/RESUME_ID_UUID