Redis Cluster, how to iterate through large set of keys in parallel

I'm trying to modify values in a large Redis Cluster via python StrictRedisCluster, and I am trying to iterate through the keys in parallel.

so far I've tried

1. keys() command which times out
2. scan() / scan_iter() which goes through the values in a single thread, which is too slow

Is there a way to scan by chunks in threads? Maybe scan per node of the cluster, or per key space? I noticed a CLI command GETKEYSINSLOT but it's not available in python Redis.

All of my keys are strings UUID format