I don't think the market of people buying used phones for the purpose of graphene is going to make a dent in profits for Google. It raises resale value maybe by say, $0, considering the price is set by the average consumer

I never considered resale value when buying a phone. Is that really something people look for?

that depends what you consider a healthy resale value, I bought my Pixel 6a with no issues for 100EUR :-) (and not because I care about Google's business, I don't have gapps in my phone, I just like good deals/VFM)