A list of previous and future OGC sprints and hackathons is available at https://www.ogc.org/projects/initiatives/ogcsprints
The previous OGC API EDR Sprint was held virtually in March 2020. Details are at https://github.com/opengeospatial/EDR-API-Sprint
OGC API website, https://ogcapi.ogc.org
Blog posts about previous sprints, https://ogcapi.ogc.org/#blogs