Hello, amazing repo! As a suggestion, you can consider using https://github.com/OpenAPITools/openapi-generator to generate a client for interaction with Aptos API. You can export the spec from {aptos_node_url}/v1/spec#/. This might save you some time and reduce the amount of boilerplate code.

PS: I'm building a project in Aptos ecosystem with a small team. We're using dart & flutter. We would love to talk to you about a potential collaboration. Let me know if you're interested, let's have a call :) You can find my email in the profile