Don't get me wrong but this sounds to me like wishful thinking. If you design the app to be decentralized, you have to provide a mechanism to incentivize node operators. If you don't do that no third party will run the node in the long run, even if the resource requirements are low. Running a node requires time and effort to keep it alive and the cost of the resources (server) is only one of the many factors. If you're the only one who runs the node, the solution is not decentralized and will have a single point of failure.

With all the respect, I don't think it's possible to create any meaningful chat solution with the proposed budget, especially the one that might compete with Discord. It might be possible to create a proof of concept but that's all. And there is a huge difference between the POC and the production-ready solution. If you want to create POC, you should mention it in the proposal and you should also present further plans and the expected budget for the next steps.