Hope somebody using Graphene OS could answer: 1. Is it very challenging to install Graphene OS? Need special cables and to know a lot about jailbreaking Android devices, or will I be fine just following instructions? 2. Is it very inconvenient to use as a daily driver? How often phone just crashes and requires a few days of debugging? Will my bank app work on it?
It's very easy. The only issue is that GrapheneOS doesn't provide a built-in way to have root privileges and if you want root on your phone securely you will have to implement that yourself or use some third-party solution (e.g. building a userdebug build, using https://github.com/chriswoope/resign-android-image , using Magisk, etc.).
We simply have far bigger priorities than dedicated the enormous resources to having a whole separate set of releases with userdebug features and an on-device root terminal which requires a special boot mode and isn't persistent. It's theoretically possible to do it in a way that doesn't throw away a lot of security, but isn't being done by anyone right now. Resigning the OS doesn't avoid the major security loss from having it integrated in the way these projects are doing. It gives the false perception of having the verified boot and other OS isolation security intact despite totally ruining verified boot by trusting persistent state and hurting OS security a lot beyond that. It is possible to do it without those problems by having it limited to the user using it, but that means preventing apps hijacking it in any way such as accessibility services.