There are a lot of starters that use Firebase for their app development. In some cases, they have to sell the products on a third-party website such as WordPress / WooCommerce in order to collect membership / subscription for their app.
The problem is that users will need to create two accounts in order to pay and use the app which is not efficient - sometimes the process may prevent potential customers from using your app.
It took me a while to build Intergate Firebase PRO and has about 185 sites that are using the plugin at the moment.
Just wondering if you are in the same situation and want to find a solution for it or if there're any requests, I'm happy to listen to.
You can look at my journey of Integrate Firebase PRO on Indie Hacker side project page.