Carlo
As a newbee, you have no idea how much preparation is needed. First of all, overall concept and architecuture, but this changes very often and doc material is like a technical study...
I assume (in the absence of a more specific description) that you are referring to to information on the official GrapheneOS website like https://grapheneos.org/faq.
First of all: As with a vanilla Android or an iPhone, it may be helpful and certainly educational, but by no means necessary, to understand GrapheneOS in depth: Once you have gone through setup via Web installer (which you just have to blindly follow step by step) and installed sandboxed Google Play the device is just as easy to use as any other.
After all, the security focus and the totally lack of user-usability, besides of the nice frontend does not allow this system to gain mor users, it will only with readymade configurations without any changes, otherwise people with throw the phone at the wall... It took me some days to get many workarounds, and some dead ends > the backup did nothing, despite many new starts and preparation exFAT ect. ect.
As others already stated: Specific information rather than generalities would be helpful to engage in a more constructive dialogue.
When a system fails at such a critical function as backup and leaves the user out in the cold, it has lost its claim to everyday usability
A solid version of Seedvault would be great for some useres, i agree. However, I think it's a bit far-fetched to use this as a valid point to deny an OS's everyday usability.
maximum security internally, but complete ignorance of usability externally.
For me personally GrapheneOS means a lot of security and privacy with very little loss of functionality. The things that make my life difficult are the factors responsible for my threat model and the way things are in the world, not my device running GrapheneOS.
In this respect, GrapheneOS is unfortunately an "ivory tower": maximum security internally, but complete ignorance of usability externally
Again, unfortunately, your post doesn't provide enough information about your exact setup.
But the fact that after flashing GrapheneOS, you can simply install Google Play Store, download apps from there, and then - with a few exceptions f.e. Google Pay maybe - your device is good to go just as any other Android device: An ivory tower looks different to me.