Not the OP and not the maintainer, but an open core example product that I love (and pay for at some companies) is MUI: https://mui.com/pricing/

They're a React UI framework with many free and some paid components.

Odoo is ERP/CRM software that comes to mind when open core is mentioned.

PS Also look into Cesium, they approached it in a smart way as well, by offering a web services tightly coupled wity, but optional from their open source product.

Also an example of open core is https://www.quantconnect.com/

Their monetisation strategy is from cloud hosting and being a data provider, very different from open core.