You 99% won’t brick it, I guarantee you. Graphene’s install is really easy. You press a few buttons on a website and never touch a terminal, aside from if you’re on GNOME. As for price, I got a used Pixel 4a 5g for 100 and newer ones won’t be as expensive as the things you might’ve gone for. Try a used Pixel 6a? (Graphene doesn’t extend software support)
Apparently people said that the Aurora Store accounts had been deleted so use an alt if possible