What do those hooks look like low level? A script polling against some ticket queue triggers the planner. Is the hand off done by using watchman which triggers agents on .md files dropped in certain directories?
“My understanding of GM is that they outsource almost everything”
I think that was an attitude from like 10 years ago. When i worked there they had all their web & mobile apps in-house. They even stood up their own hosted PCF network into the more recently partnered with Azure.
I’m pretty sure you’re describing things AWS Gateway is all capable of. It can proxy s3 to allow public download and can create user pools in cognito for auth