Not sure about Debian, but on Arch Linux, hibernation with FDE works perfectly on my Framework laptop. It took a little to setup; I use a swapfile for my swap. And it exists on my encrypted drive. You know your use case best,I found for my usecase, a separate swap partition (to say nothing about two separate ones) was restrictive and unnecessary. A swapfile works well and lives on an encrypted drive. No need to tinker too much beyond that. Check out the Arch wiki, it might not align 100% with Debian but those wikis are super informative and can teach you how the process works so you can apply to Debian.

https://wiki.archlinux.org/title/Dm-crypt/Swap_encryption#With_suspend-to-disk_support

I have this working on Debian like how you have it set up, everything on an encrypted lvm volume, except for boot and efi. Just one disk though. When waking up, it asks for the password like it does during normal bootup. It then restores RAM from the encrypted swap after you type the password. I think it worked out of the box, but it has been a while, so not 100% sure if I had to enable this somehow. Anyway this looks good to me.

If you manually run systemctl hibernate, does that work? Assuming this also does not work, you need to look at the logs during the failed hibernate attempt. Probably something like sudo journalctl -f and/or sudo dmesg -wH (for kernel logs). Open this up in two terminals, run systemctl hibernate and observe any errors or warnings.

It's possible this is a hardware/driver issue, i.e. a driver prevents hibernation or fails at it. You may be able to figure out which driver/device is responsible by looking at the logs.

You have to use two swaps if you already use one swap, because one will be used when the system is on, but the second will be used to set the RAM content + the 1st content into SWAP (if any), otherwise, it would fail.

Then, find the hibernation swap uuid:

sudo swapon --show
lsblk -o name,uuid

Then

# /etc/default/grub
GRUB_CMDLINE_LINUX_DEFAULT="resume=UUID=xxxx"

#/etc/initramfs-tools/conf.d/resume
resume=UUID=xxxx

# bash
sudo update-grub
sudo update-initramfs -k all -u

# to hibernate on lid switch
# /etc/systemd/logind.conf
HandleLidSwitch=hibernate

Then reboot :)

Note: this method works wonderfully, I use it personally. Just be aware that the hibernation swap content is not encrypted, so you're vulnerable if your laptop is stolen while hibernated.

I would need your password to be able to replicate, as well as your mother's maiden name, city of birth and first pet's name.

hibernation is in general not supported with full disk encryption, and is not recommended. you can do it but it's a hassle and will lead to hangs on wakeup if you don't configure it correctly. i gave up on it.