Why full disk encryption is important: what happens when you switch servers or providers: can you be sure the disk gets wiped properly?

Or when your disk dies and gets replaced, what happens to the old disk? Will they physically destroy it or just throw it in the bin?

When encrypted, it doesn't matter; no one will get data off of them. That's why you encrypt servers.

LUKS may not make your server meaningfully more secure. Anyone who can snapshot your server while it's running or modify your unencrypted kernel or initrd files before you next unlock the server will be able to access your files.

This is a little oversimplified. Hardware vendors have done a lot of work in the last 10-20 years to make it hard to impossible to obtain data this way. AMD-SEV for example.

There are other more realistic attacks like simply etrackt the ssh server signature and MITM the ssh connection and extract the LUKS password.

To me, the nonstandard port is mostly nice for reducing log spam from scripts. The risk is that using a nonstandard port lulls one into a false sense of security and overlook good sshd practices. Good sshd practices will prevent the script-kiddies just as well as the non-standard port, while a non-standard port will not challenge a targeted attack. And, if you interact with multiple servers, it can be inconvenient to remember a different port for each one.

I use nonstandard ports for just about everything such as Docker containers, including ssh. However, modern bots are quite capable of scanning your server for vulnerabilities, CVE, zero day, and SSH. A non standard SSH port does reduce noise a bit but isn't a reliable defense against scanners.

The whole port range can be scanned in under a second. A real attack does not care if your ssh port is 22 or 69420. Changing Port is just snake oil.