Bad Superblock while mounting an ext4 Disk

I wanted to migrate my Data to a larger Disk for my secondary Drive for my Synology NAS. I tried to Mount the Disk on a Rapsberry to do a Filetransfer to the new Disk on the Synology. But on the way to get the Data from the old Disk I got superblock errors. Maybe I hit a wrong Command to mount the Disk which was previously used as ext4 Disk in a Disk Pool with only this single Disk. (Last Time I used mdadm to migrate the Single Disk RAID and worked like a charm). So now I am unable to mount it and have no clue how to continue getting back the Data. Here are some commands I tried to debug:

pi@pi4:~ $ lsblk
NAME        MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda           8:0    0  7.3T  0 disk
├─sda1        8:1    0  2.4G  0 part
├─sda2        8:2    0    2G  0 part
└─sda3        8:3    0  7.3T  0 part
mmcblk0     179:0    0 29.5G  0 disk
├─mmcblk0p1 179:1    0  256M  0 part /boot
└─mmcblk0p2 179:2    0 29.3G  0 part /

pi@pi4:~ $ sudo mount -t ext4 /dev/sda3 /mnt/tmp/
mount: /mnt/tmp: wrong fs type, bad option, bad superblock on /dev/sda3, missing codepage or helper program, or other error.

pi@pi4:~ $ sudo fsck.ext4 /dev/sda3
e2fsck 1.44.5 (15-Dec-2018)
ext2fs_open2: Bad magic number in super-block
fsck.ext4: Superblock invalid, trying backup blocks...
fsck.ext4: Bad magic number in super-block while trying to open /dev/sda3

The superblock could not be read or does not describe a valid ext2/ext3/ext4
filesystem.  If the device is valid and it really contains an ext2/ext3/ext4
filesystem (and not swap or ufs or something else), then the superblock
is corrupt, and you might try running e2fsck with an alternate superblock:
    e2fsck -b 8193 
 or
    e2fsck -b 32768

pi@pi4:~ $ sudo mke2fs -n /dev/sda3
mke2fs 1.44.5 (15-Dec-2018)
Creating filesystem with 1952301396 4k blocks and 244039680 inodes
Filesystem UUID: c98ad2b3-3e8a-426c-a0f7-b06ed0279fa3
Superblock backups stored on blocks:
        32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
        4096000, 7962624, 11239424, 20480000, 23887872, 71663616, 78675968,
        102400000, 214990848, 512000000, 550731776, 644972544, 1934917632

pi@pi4:~ $ sudo mdadm --examine /dev/sda
/dev/sda:
   MBR Magic : aa55
Partition :   4294967295 sectors at            1 (type ee)

I tried to use a superblock stored in the blocks showed in the previous mke2fs command output but without success (and I tried more superblocks then shown in the example).

sudo e2fsck -b 32768 /dev/sda3
e2fsck 1.44.5 (15-Dec-2018)
e2fsck: Bad magic number in super-block while trying to open /dev/sda3

The superblock could not be read or does not describe a valid ext2/ext3/ext4
filesystem.  If the device is valid and it really contains an ext2/ext3/ext4
filesystem (and not swap or ufs or something else), then the superblock
is corrupt, and you might try running e2fsck with an alternate superblock:
    e2fsck -b 8193 
 or
    e2fsck -b 32768

pi@pi4:~ $ sudo dumpe2fs /dev/sda3 | grep -i superblock
dumpe2fs 1.44.5 (15-Dec-2018)
dumpe2fs: Bad magic number in super-block while trying to open /dev/sda3
Couldn't find valid filesystem superblock.

Maybe you can give me an Advice how to get the Data from the Disk. Thanks in Advance! Edit: Add more Information as requested

pi@pi4:~ $ sudo file -s /dev/sda3
/dev/sda3: data

pi@pi4:~ $ sudo fdisk -l /dev/sda
Disk /dev/sda: 7.3 TiB, 8001563222016 bytes, 15628053168 sectors
Disk model:
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 4096 bytes / 33553920 bytes
Disklabel type: gpt
Disk identifier: F6E21726-C437-47C8-BA95-FF84072B6C52

Device Start End Sectors Size Type
/dev/sda1 2048 4982527 4980480 2.4G Linux RAID
/dev/sda2 4982528 9176831 4194304 2G Linux RAID
/dev/sda3 9437184 15627848351 15618411168 7.3T Linux RAID