The architecture I like is either modular monoliths, or if you really need isolation, a FaaS setup with a single shared function library, so you're not calling from one function service to another but just composing code into a single endpoint that does exactly what you need.

HTTP RPC is the devil.

I generally agree although I think gRPC and using it with json is awesome, it's just that like with most of these tools, the investment in setup/tooling/integrating them into your work has to be worth what you get out of them.

I actually used to do FaaS at GCP and now through my startup am working on a few projects for cloud services, tooling around them, and composable/linkable FaaS if you're interested! A lot of this logic isn't in our public repos yet but hit me up if you want a try fully automated Golang->proto+gRPC/http+openapi+ts bindings+client generation+linker-based-builds.

A project we started for "modular monoliths" that need local state but not super high availability as databases is at https://github.com/accretional/collector, but I had to put it on pause for the past few weeks to work on other stuff and figure out a better way to scale it. Basically it's a proto ORM based on sqlite that auto configures a bunch of CRUD/search and management endpoints for each "Collection", and via a CollectionRepo additional Collections can be created at runtime. The main thing I invested time into was backups/cloning these sqlite dbs since that's what allows you to scale up and down more flexibly than a typical db and not worry as much about availability or misconfiguration.