The website needs to be open source too.
You being able to revise the terms of service with no notice is a deal breaker.
The privacy policy might not be GDPR compliant due to changes being effective immediately instead of being consented to.
Why are you using Slack instead of something more open (like self-hosted Mattermost)?
Really appreciate it!
You need to be super transparent about what sort of cut you are taking from funders and how you are funding the OpenTeams project itself and what expenses that funding is paying for (salaries, development, servers etc).
The OpenPartner's are responsible for creating the product roadmap in liaison with the development team. This includes a clear budget for where the money is going, just as you described.