Instead of looking for a removable SSD consider setting up some kind of syncing and backup solution. A removable ssd doesn’t protect you from theft or ransomware. I use a combination of time machine, backblaze and syncthing to make sure all my data is synced across my machines and backed up locally and in the cloud.
A removable SSD does ensure that my laptop doesn't become trash after I use it long enough. For many people (myself included) no computer can truly feel "perfect" unless it can be run in relative perpetuity.
