Or Google Play, for that matter!

(I don't really care because I find the idea of hooking your credit cards to a third party to pay with your phone creepy to begin with, but are there any non-Google-Pay alternatives for GrapheneOS or Linux phones?)

Google claims the google playstore is safe and the only way to avoid malware. Ironically it was like 65-70% of all malware on android came from the playstore.