Congratulations! By coincidence, your startup reminds me of the use case of smart contracts. I always tell people that smart contracts are cool because you can program money however you like. One of the examples is payment splitter.

Recently, I coded up the payment splitter smart contract.

https://mamba.black/documentation/payment-splitter/

Yours is bill splitter. But technically, you can code up the bill splitter as a smart contract too.

That's all. I wish you success. Who knows my story is useful for you. I don't know. Maybe a few years later, you want to expand your service to cryptocurrencies. :)