Update I have come to a decision. Thank you to all who contributed suggestions. Please feel free to keep the discussion going to help others.
The main concern is going to be hardware reliability from wear and tear. That’s the value of buying refurbished, for which there are several reputable retailers online (some of which selling degoogled phones with their own OSes). On the software side, since I’m presuming the focus of this discussion is installing grapheneos, its not really a concern since you’re going to be reflashing the device