If your "opt-in platform features" and "interface to allow permissioned access to data and capabilities between different apps" is more expressive/discoverable than eg Cloud Foundry's "Service Broker" approach[0], then I am pretty excited! I run a lot of disparate services which don't interoperate except through explicit workflow automation pipelines (I use ConcourseCI to eg upload images to Immich [1] albums, but others might use n8n[2] for the same purpose).

The "workflow automation" approach is a lot of resource overhead and broker-config maintainance, but my kingdom to be able to arbitrarily compose apps' states, eg commutimemap.com + Craigslist.

0. https://www.cloudfoundry.org/technology/open-service-broker-...

1. https://github.com/gavmor/immich-concourse-resource

2. n8n.io