RDS Upgrade - Postgres 12.7 -> Aurora - best way with zero or little downtime

Good evening ... as the subject states, we are currently running an RDS version of postgres 12.7 and wish to migrate over to Aurora. I would assume the easiest would be to create an aurora read replica, test all functions (including postGIS), and once confirmed things work, promote that and should be good however the create aurora read replica is not showing on the console. I saw a few threads about that being a big but that was months ago.

This database gets thousands of updates every minute, so really trying to keep the downtime to nothing or as little as possible, so any guidance or help is appreciated.