Assuming you don't have an unlocked bootloader or custom recovery, the best shot you have is an adb backup. It can backup app apks and app data to some point. Apps like Whatsapp and Facebook cannot be backed up this way as it requires a specific data migration method and login.
If you do have root/custom recovery, it can make a full backup but the image would have difficulty booting on other phones/emulators. Don't attempt this route if you see a locked bootloader as the process of unlocking will wipe everything
No perfect solution. The best you could do is to migrate/recreate the phone in an emulator and backup the emulator
If you use ZFS you can use the SSD as L2ARC. However, you do have to have enough RAM before this will net any gain in performance so it really depends on what you got.