GitLab or GitHub. You can create groups and projects and manage members.
You can create issues with templates to lower the skill necessary to write up a good issue. You can create milestones (have these issues closed by next month). You can have discussions on issues, and be able to track and measure progress and have everyone know why an issue is taking longer than necessary and chiming in to help.
You can have a Wiki so that you can simplify onboarding new members to the team. Here's how we're structured, here's the people to contact in each continent.
If the internet connection is lousy, you can create issues by sending an email, and you can comment by replying to emails instead of doing it through the web application. This has been validated by us as we had a member who could not open web pages in a very remote location during one year, but they were able to do email. We simply /cc'd them in the issue template and they were able to stay on top.
You can tie it to Slack and on Slack add channels for different continents while maintaining communication lines. You want to reach the Africa team? Post on the channel.
You can create issues right from Slack and reduce friction. Each member has a profile with their contact information.
You can save minutes of meetings (meeting notes) on GitLab so everyone knows what was discussed within different teams and search for a topic.
You can use Jitsi for video calls if any and put that into playlists on YouTube for different continents. Africa playlist, Europe playlist, etc...
So you can align people, track progress, and get everyone on the same page, effectively creating leverage and amortizing the time spent on anything and making sure a message gets to as many people as possible.
There are a lot of huge, complex, software projects being built by distributed teams around the world that function like this.