Challenges in Tracking Subscription Events with Mixpanel in Flutter App

Hi everyone, We built a subscription app via flutter and utilize Mixpanel for our event tracking. Subscription modeling has been an absolute pain point for our dev team and the Backend design looks rather… ugly. We want to track basic subscription events in our mixpanel app project but missing the knowledge on how to approach this issue. We would like to track the following events:

And following event parameters: “user_id” = USER_ID_FROM_BACKEND”, “subscription_plan” = Name of subscription “price”: = Price of subscription “currency”: “USD”, “platform”: “iOS”, // or “Android” I as an analyst was told that implementing events such as ‘trail started’ or ‘trail cancelled’ would be way too complicated and instead a singular event subscription_bought with a parameter indicating if the subscription was attached to a free trail or not (NOT HELPFUL WHATSOEVER!!!! 😤). We do not want to utilize an MMP or 3rd parties such as RevenueCat - believe me I have to mentioned it every time. Is it really that difficult to connect with the iOS: StoreKit and Google Play Billing Library to retrieve reliable subscription event data connected to our BE user_ids (DISTINCT_ID) for LTV calculations and more? Any help on this is greatly appreciated - the more the better since our team seemingly has platooned on this issue. Thanks!🙏🏻