Can I migrate my Pay-As-You-Go subscription through open to a CSP subscription?

It’s the resources within one subscription that can be migrated to Azure through CSP subscription. Any existing credits or entitlements in one subscription cannot be moved to another subscription. The process involves a partner subscribing to Azure through CSP, while they hold on to the existing Open subscription and start migrating the resources from one to the other. Refer to the blog here for a detailed read around this.