I’m curious what about Graphene you think would prevent certain demographics from using it as a daily driver? There are pretty well no downsides to using it compared to a first party ROM aside from not having certain things like Google Assistant baked in. It has automatic updates, you get the play store and services if you want them, it even has android auto. It’s also the most rock solid android experience I’ve had since I switched from iOS in 2012 or so.
Obviously a stereotypical grandparent would need someone who knows computers to do the initial install and setup, but after that it’s pretty well just set and forget.
I run two multimonitor systems with different DPIs and 2.5gbe and they both run great. What issues are you hitting?