Thanks for your response, I appreciate it! We're doing a full migration, so our GIS and DB servers will all be migrated at one time. We won't have any VPN tunnels linking AWS GIS to on-prem DB. We know that latency would probably be a nightmare.
Since everything is being migrated, all hostnames, DB servers, etc. will be staying the same, so I'm thinking there won't be any FQDN or registered data source issues. I'm not aware of any modifications that will need to be made (besides the DNS pointing to AWS instead of on-prem, but that's beyond my scope of responsibilities).
We considered WebGISDR, but it's kind of our backup method in case list-and-shift doesn't work. The lift-and-shift method is a little more straight forward for us to use.
Anyway, thank you for your response! I was just making sure we aren't setting ourselves up for failure, and I'm glad to hear that other people have used this migration strategy before.