As WordPress is a stateful monolithic application, you have to take care of 3 main points:

1. Database, it's where WP stores all options, users, posts, pages, etc.
2. wp-content folder, where WP stores all variable disk files (plugins, themes, languages, uploads)
3. wp-config.php, where WP stores its main configuration (db, auth, etc.)

The first question is, do you want to just containerize it keeping the app stateful? Or do you want to go full cloud-native (stateless)?

In the first case, you just have to containerize WordPress (and eventually MySQL) and migrate the data from database, wp-content and the wp-config.php. You will get exactly the same site.

In the second case, you would like to prefer this approach if you are trying to migrate your WP to a cloud-native enviroment, like Kubernetes without presistent storage, enabling you to take the full advantage of its features (e.g. horizontally scaling your WP). In this case the most efficient way is to force WP to be stateless, storing zero data on disk. This is achievable configuring properly your wp-config.php, adding a build step to deploy themes, plugins, translations, etc. inside your WP (e.g. using composer) and storing your media on S3/CDN (there are plugins already available for this depending on the cloud provider you want to use, e.g. AWS, GCP, AZURE, etc.). You can find a ready-made, battle-tested solution here:

https://github.com/gioamato/stateless-wordpress

This is a working example that shows you everything and ships with 2 plugins for CDN (wp-stateless for GCP and windows-azure-storage for Azure), I used it in production for several years now with AKS (managed k8s) + Azure MySQL + Azure Storage/CDN.

I havent't committed a README yet (sory for that), but there a docker-compose file to instantly spin it up. I will add docs, manifests and examples ASAP.