In reply to @steeringwheelrules:tchncs.de
are there any examples of zfs setup that works with hibernation? as far as I'm aware it only needs to not be used for the swap partition, but the rest of the drives (including nixos) can be zfs, right?

This might work for hibernation:

  disko.devices = {
    disk = {
      nvme0n1 = {
        device = "/dev/nvme0n1";
        type = "disk";
        content = {
          type = "gpt";
          partitions = {
            boot = {
              priority = 1;
              start = "34s";
              end = "2047s";
              type = "EF02"; # for grub MBR
            };
            ESP = {
              priority = 2;
              start = "2048s";
              end = "2099199s";
              type = "EF00";
              content = {
                type = "filesystem";
                format = "vfat";
                mountpoint = "/boot";
              };
            };
            luks = {
              priority = 3;
              start = "2099200s";
              end = "100%";
              type = "8309";
              content = {
                type = "luks";
                name = "crypted-nvme0n1";
                settings = {
                  allowDiscards = true;
                };
                content = {
                  type = "lvm_pv";
                  vg = "nvme0n1";
                };
              };
            };
          };
        };
      };
    };
    lvm_vg = {
      nvme0n1 = {
        type = "lvm_vg";
        lvs = {
          # LVs are created in alphabetic order for some reason
          # Prefixing them with a letter like this ensures desired creation order
          a_swap = {
            size = "64GiB"; # equal size to maximum available RAM
            content = {
              type = "swap";
            };
          };
          z_data = {
            size = "100%FREE";
            content = {
              type = "zfs";
              pool = "root";
            };
          };
        };
      };
    };
    zpool = {
      root = {
        type = "zpool";
        rootFsOptions = {
          compression = "lz4";
          "com.sun:auto-snapshot" = "false";
          mountpoint = "none";
          reservation = "16G";
        };
        postCreateHook = ''
          zfs snapshot root@blank;
          zfs snapshot root/nixos@blank;
          zfs snapshot root/nix@blank;
          zfs snapshot root/home@blank;
          zfs snapshot root/persist@blank
        '';

        datasets = {
          nixos = {
            type = "zfs_fs";
            mountpoint = "/";
            options.mountpoint = "legacy";
          };
          nix = {
            type = "zfs_fs";
            mountpoint = "/nix";
            options.mountpoint = "legacy";
          };
          home = {
            type = "zfs_fs";
            mountpoint = "/home";
            options.mountpoint = "legacy";
            options."com.sun:auto-snapshot" = "true";
          };
          persist = {
            type = "zfs_fs";
            mountpoint = "/persist";
            options.mountpoint = "legacy";
            options."com.sun:auto-snapshot" = "true";
          };
        };
      };
    };
  };

But be aware of zfs#12842 - make Linux hibernation (suspend-to-disk) more robust and nixpkgs#208037 - nixos/zfs: mitigate data loss issues when resuming from hibernate

You might also need these to enter the danger territory (make yourself familiar with zpool recovery strategy):

  boot.zfs.allowHibernation = true;
  boot.zfs.forceImportRoot = false;
  boot.zfs.forceImportAll = false;

                    "/swap" = {
                      mountpoint = "/.swapvol";
                      swap.swapfile.size = "20M";
                    };

https://github.com/nix-community/disko/blob/2bf3421f7fed5c84d9392b62dcb9d76ef09796a7/example/luks-btrfs-subvolumes.nix#L57-L60

Is this a swap partition or a swap file?