It is possible, in fact it's not as hard as you think it is. Unfortunately, I respect the work of the developers so I will not be disclosing how you go about this but if you are determined enough you will find it.
But many of you need to understand is there are fewer and fewer reasons to actually require root as years go by, but there are some situations some scenarios some living situations were root is required to achieve certain things such as 5G in a country that does not natively support it.
If this user wishes to jeopardize his security model by pursuing root that is on him.
It must be noted, if you do decide to pursue and achieve root, nobody here on this forum will provide any kind of assistance if and when an issue may arise. It is no longer grapheneOS and they do not support root scenarios