This is really cool!

Tip for others: You can click the lines in between components to add text to them

One question though, when I click on something, like "API Gateway", in the "Properties" panel it lets me add REST/GQL/gRPC etc endpoints

These seem not to do anything though? What is the purpose of the "properties" on most of the components?

Seems only one that does anything is the "Shard Database" button on a Database component