This is a major dealbreaker that it needs to be called out earlier. Not only is this an interface you adhere to to use their service (incoming event, outgoing

This is a major dealbreaker that it needs to be called out earlier. Not only is this an interface you adhere to to use their service (incoming event, outgoing response), that type of coupling is fair and expected, but the underlying runtime is custom without full support for standard APIs?! What's the upgrade path? Can they port things over in a reasonable amount of time? Is it well documented what's supported and what isn't? Imagine developing against this and resolving these issues as they come up. Oof. I'll use Azure or AWS.