Retrieve the "selling plan id" from the Shopify Admin API

[thoger]

Hi community, happy new year

Is it possible to retrieve the "selling plan id" from the Shopify Admin API?

I have read the docs and I am trying to retrieve the selling plan id from some resource ala the SellingPlan resource described here https://shopify.dev/api/liquid/objects/selling-plan or the SellingPlanGroup as described here https://shopify.dev/apps/subscriptions/selling-plans. 

Any help is highly appreciated! Thank you.