Can Ethereum smart contracts be used to securely hold user deposits?

We have a website with a system where users need to deposit money as a security deposit or collateral (Forum).

For security and trust reasons, I don't want the money to be held directly by us. Instead, I'm looking into whether we could use a blockchain smart contract or some other decentralized solution to hold the funds.

The idea is that people who advertise/promote content that has a deposit attached to it would receive a commission, for example 10% or 15%, based on predefined rules. The commission would be handled automatically by the system, while users would still be able to see and track their funds from their own wallets at all times.

We are also considering creating a kind of hot wallet network that users could use to send and receive funds between each other within our platform.

My main question is: would something like this be possible to build on the Ethereum network using smart contracts?

I'm still researching the technical side of this and I don't know all the details yet, so I'd really appreciate any advice or suggestions from people who have experience with Ethereum, smart contracts, or similar systems.

Thanks in advance, and I appreciate any input.