We manage a couple dozen GCP projects, and I've never figured out how to list all the enabled API services for each project on the website. There is a way to do it via Cloud Shell by running the console command: gcloud services list
If I visit https://console.cloud.google.com/apis/library?project=PROJECT_NAME, I can see whether a specific API service is enabled, but then I'd have to individually visit 300 separate API pages per project, which is not feasible.
There has to be a better way for end users to do that without having to install Google Cloud SDK.
As LundinCast and Kamelia Y commented, the enabled API libaries are listed on the main Dashboard page. They're under the Traffic, Errors, and Median latency charts.