Is AWS a requirement? I've just started a project that is roughly... 75% Azure Functions and so far it's been a dream. Between the triggers and the outputs, and being able to run functions locally in VSCode I feel like it's the perfect way to "glue together various bits and pieces" as you said. Obviously a lot of the triggers are Azure-specific but between HTTP and Service Bus Queue/Service Bus Topic you should be able to do just about anything you need.
On the plus side of having a lot of the pieces in Azure, if you're lucky enough to have an input and output match (e.g. you want to persist SB Topic messages into a SQL API CosmosDB instance) it's a half dozen lines of code and you're done.
On the plus side of having a lot of the pieces in Azure, if you're lucky enough to have an input and output match (e.g. you want to persist SB Topic messages into a SQL API CosmosDB instance) it's a half dozen lines of code and you're done.