Egress costs alone make leaving pretty much a non-starter once you're entrenched.
Leaving really involves running two systems in parallel for a bit and gradually doing a changeover - blue-green in production between two different clouds. Which is not cheap/free either, you are actually going to increase your costs significantly as you leave.
Appropriately sneaky: https://aws.amazon.com/snowmobile/ appears[1] to allow export of petabytes of data but then the FAQ reneges “Snowmobile does not support data export”[2].
[1] tagline: “Migrate or transport exabyte-scale datasets into and out of AWS”.
Not an answer for the Exabytes they appear to be falsely advertising they can export in the tagline. A mediocre answer for Petabytes. I agree Snowball Edge is one answer for Terabytes: “HDD storage capacity: 80 TB” - https://docs.aws.amazon.com/snowball/latest/developer-guide/...
Leaving really involves running two systems in parallel for a bit and gradually doing a changeover - blue-green in production between two different clouds. Which is not cheap/free either, you are actually going to increase your costs significantly as you leave.