Use dropbear? Dropbear is an ssh server, but it is a minimal one which can be embedded in the initramfs image. I think in ubuntu the package is called dropbear-initramfs. It is used for decrypting in early boot. There are great in structions for all this if you search.
The solution would then look like: wol, ssh into it, you are prompted passphrase, once entered you are thrown out, computer continues boot, you are done.
This is what I've been doing for a few years now.
I do use dropbear-initramfs. However the issue if I power off or the power goes out while I am unlocking the computer, I will be unable to reboot the computer using WOL. Is there something like dropbear-initramfs but instead of it being a SSH server for the LUKS lockscreen, it is a WOL enabler?
Sorry, so your motherboard/network card resets the WOL feature on a second reboot? Or what is the problem?
here is a guide you might be able to get some ideas from on how to set it up
you will not be able to get the WOL to work as long as you require a password to boot. if you need full disk encryption, look into storing the encryption password in TPM, enable secure boot and password protect bios/system setup with a locked boot order.
as long as your system requires input from you to start, it will always stop at the luks unlock step, unless you find another place to store the keys to allow unlocking without user input.
it could work if the computer suspended instead of powering off, but then it will fail again in a case of power loss.
hope this helps a bit, and good luck. seems like a fun project.
Whether you're a seasoned pro or the noobiest of noobs, you've found the right place for Linux support and information. With a dedication to supporting free and open source software, this community aims to ensure Linux fits your needs and works for you. From troubleshooting to tutorials, practical tips, news and more, all aspects of Linux are warmly welcomed. Join a community of like-minded enthusiasts and professionals driving Linux's ongoing evolution.