If you don´t mind, you can use my changes. This changes worked for me in ubuntu 16.04 and 20.04. I have proposed the change some years ago... If I remember, I have used the sddm.service file as template.
Stef
Hi Stef, not sure what changes you proposed in the past, but if you can point us to them we will take a look. Is it something similar to what is found here https://bugs.pearsoncomputing.net/show_bug.cgi?id=2806? Or something different?
Cheers Michele