I've built some nice small frameworks for projects on both CloudFlare Workers and GCP Functions that do exactly this. They are so simple to build that I can't imagine needing to even open source them... but maybe should write up a blog post on the details at some point. So many people seem to miss this detail for some reason.

The main benefit is that it sure is a lot easier/faster to deploy one function than one for each route (CI/CD goes so much faster). As well as the cold starts.