I worte a guide last year on how I do network bound encryption - that is the disk will automatically decrypt at boot if it’s connected to my home network, but not if the disk or machine is removed from my house. The advantage over the dropbear method is that you can set unattended upgrades to auto reboot your server whenever it installs security updates, and it’ll come back up with no manual intervention from you.
The ultimate bad bot blocker (https://github.com/mitchellkrogza/nginx-ultimate-bad-bot-blocker) does the heavy lifting for me, it updates multiple times per day to add and remove IP addreses and bot referers. It does need some monitoring though, some of the rules wildcard a bit hard and will catch mastadon servers with unusual names for example.