>>Effraf+JM
I'd be interested in more specifics here. I've been in a few bootloops with GrapheneOS early on but I've always been able to get out of them by keeping cool and not prematurely trying to reflash and wipe. Eventually the phone always booted (I think that it's due to the A/B partition system where eventually the phone will try to boot the other "working" partition again. But sometimes this would take a while).
It hasn't happened in a year though and I've been happily upgrading lately. I'm not saying you couldn't have run into a unique bug but I'd find it surprising if your phone was really left completely bricked except for reflashing/wiping it.