I did it on a r6.24xlarge RDS instance and the CPU wasn't doing much during the operation. IO peaked at 40k IOPS on EBS with provisioned IOPS, I'm not sure if a local disk would be any faster but I already know that rewriting the table and creating the indexes are all single threaded so there isn't much you could gain.

Once I got the logical replication setup to work I changed 20 tables on the replica and made the switch with 15 minutes of downtime. That saved me a lot of long nights.

You can get an idea of how long this could take by running pg_repack, it's basically doing the same thing: Copying the data and recreating all the indexes.