One is about all the steps of zero downtime migration. It's widely applicable.
The other is the decision to replace a cloud instance with bare metal. It saves a lot in costs, but also the loss of fast failover and data backups is priced in.
If I were doing this, I would run a hot spare for an extra $200, and switched the primary every few days, to guarantee that both copies work well, and the switchover is easy. It would be a relatively low price for a massive reduction of the risk of a catastrophic failure.
You're describing Hetzner Cloud, which has been like this for many years. At least 6.
Hetzner also offers Hetzner Cloud API, which allows us to not have to click any button and just have everything in IaC.
i hardly ever visit their website, everything from terminal.