Yes, SimpleDDP is a good fit for that use case (you can also expose Rest or GraphQL endpoint from Meteor backend but it won’t be real-time).
We do use Meteor frontend as well, but we use SimpleDDP to achieve JAMStack for specific use cases (public mobile PWAs) and we prefer SimpleDDP over GraphQL for the simplicity, elegance and built-in realtime features. I really think SimpleDDP should be pushed further and be part of the community packages. I think “SimplePWA” (DDP + JamStack + Meteor + Galaxy) is the fastest and simplest way to get a mobile app out there and it’s a natural extension and development of the Meteor story.
Library seems pretty rich. I got a silly question to ask since I never had experience using npm.packages in a plain php+html+JavaScript website. Is it possible in any way to use npm libraries in plan html+JavaScript based website by using require() import or export?