We just shipped a new feature that allows you to see keyspace resizing progress at a per-shard level. The architecture diagram will indicate when a keyspace is resizing. You can click "View" to see progress for each shard:
CLI
As of pscale version 0.220.0, you can check keyspace rollout progress with pscale keyspace rollout-status <database> <branch> <keyspace>.
API
The show keyspace rollout endpoint is now available.
For more information, see the PlanetScale architecture documentation.