Use an Ubuntu live USB, all recent versions of Ubuntu have ZFS drivers baked into the live environment. Then you should add your new SSD to the ZFS pool, and remove the old one from the ZFS pool. Your m.2 WiFi slot should be able to host the 2nd drive while you do this, but if not you can use an external USB housing for it, you’ll just have to make sure that the ZFS pool knows its UUID so that it knows it’s the same drive.