There is, in fact, zero hassle. "It just works
"
Also, GrapheneOS updates never remove functionality or battery life.
But yes it only works on supported devices - in related news, iOS does not run on unsupported devices, so what's your point?
I know I can buy an iOS device and get support from the vendor without hoping that some third party will support it out of the kindness of their heart and know that it supports apps from the AppStore.
I can do the same thing with Windows. Microsoft figured this out almost 30 years ago.
Apple just released a security update for the 2013 iPhone 5s earlier this year.
Apple has had security updates for the following iPhones this year: iPhone 5s, iPhone 6, iPhone 6s, iPhone 7, iPhone 7Plus iPhone 8, iPhone 8 Plus, iPhone 10, iPhone 10XR, iPhone 10s, iPhone 11, iPhone 11 Plus, iPhone 12, iPhone 12 Pro, iPhone 12 Pro Max, iPhone 13 Pro, iPhone 13 Pro Max, iPhone 14, iPhone 14 Pro Max, and two generations of iPhone SEs and a couple of iPhone Minis
I ran CalyxOS on my Pixel 3XL and while it delivers on the privacy focus, I think most users would find it too irritating for long term usage. I ended up replacing it with Pixel Experience, which as the name implies is pretty much an up to date version of the stock ROM.
I couldn't be so cold as to give Graphene to my grandmother. That said, I am writing this from Graphene myself, having never touched an Apple device in my life.
With Google Play Services and the Play Store enabled there's almost zero usability difference between the standard Google Pixel Android and GrapheneOS.
Security updates for 5-7 years.