How would you handle payments for the use case of being mediator between customers(public) and sellers?

My sister is planning to build a app in which she would be bridging customers and sellers. Here is use case: 1. userA loads their account( our mobile app) with 100$, and userB loads their account(our mobile app) with 50$* 2. Later user places order from that account to a seller. 1. userA's 20$ deducted from our mobile app and 2. Sent to seller 3. Seller hands over product to userA Ideas on handling funds on back end by the mobile app Option 1: *Let’s consolidate multiple users' funds to common business account(/paypal/stripe/whatever) of the company. So, the transaction sheet in Backend looks like userA deposited 100$ to mobApp account on 01/01/2022 userB deposited 50$ to mobApp account on 01/01/2022 Total value of all users money on 01/01/2022 = 150$ userA purchased 10$ worth of products from sellerA on 01/02/2022 BE notes down that from common pooled amount 150$, 10$ has been deducted for userA on date 01/02/2022 userB purchased 5$ worth of products from sellerB on 01/02/2022/ Now common pool money goes down to 135$ and 5$ was against userB userA returns the item and get 10$ back from sellerA to userA on 01/03/2022. Common pool money is now 145$ Option 2: Stripe Treasury equivalent Stripe and may be few other companies provide options to set up a bank account equivalent for each users. Each user can have their own credit card, checking account etc. But I feel this might be overkill for our use case. Questions: a) Do you see any issues with Option 1? ( The main issue from the app side is to handle each customer's transaction under one blanket account and disburse funds to sellers) b) Any other alternatives other than these two options? c) This is the overall flow userS(*…1) ==> our mob app account (1…*) ==> seller Account Here in first step, we as biz have to pay some fees for processing user's card. Then while transferring funds from our account to seller, seller bears another processing fee. Any ideas to reduce this burden anywhere in the chain? d) Any specific merchant services/product you would recommend? #tech #paypal #square #stripe #bankofamerica #marqeta #visa #americanexpress