There’s a Form Embedder resource which utilizes Google Forms. You’re able to look at responses in your browser without connecting to the game. Another solution is sending feedback to a datastore and listing through the entries in-game or through the Open Cloud API. If you can afford a data storage service, that can be used to save feedback as files with HTTP requests. The datastore and storage service solutions allow you to edit those data entries yourself to provide responses/confirmations for user feedback, similar to an e-mail thread.
edit: One-way feedback is now a feature. Liking/disliking a game shows an option to send anonymous feedback to developers. The feedback can be read in the Creator Hub page for a game, in Audience > Feedback.