I've published an article with practical guidance on migrating from Apigee Edge to Apigee X, looking at the whole migration project lifecycle.
As there hasn't been a lot of articles on this, I have focused on the recommended approach for migrating each component from Edge to X (e.g. Developers, Companies, API Products, etc).
Hopefully this provides useful insight to project planning, architects, and technical leads when migrating from Edge to X.
https://www.sonrai.com.au/insights/migrating-from-apigee-edge-to-apigee-x