For something as important as work files. I'd never rely on one backup. Consider a backup service like Backblaze for a secondary remote backup. Then you'll have a backup which won't be affected by something local like fire, flood or theft. Or you can just use a sync service like Onedrive, Google Drive, Dropbox or iCloud as a secondary source of storage. True they aren't a real backup. At least if you have one real backup (for accidental deletions and archives). Then it is added to a sync service for current files. It should be good enough for most people.
An argument for SSD is backup time. If you are using Time Machine. Which I don't use. It performs multiple times a day. Each one dragging down system resources while running and can take a long time to accomplish. An SSD will likely take much less time. Since it can scan and adjust the backup much more rapidly on an SSD.
I prefer something like Carbon Copy Cloner. Then you have a bootable backup. Plus, you aren't wasting space on old files and file revisions. My view is the Trash already gives you a second chance. When you delete a file it should be gone for good.
That's good to hear. I was looking at this one that was also advertised around the time I got my computer, but it's still quite expensive.
Mind telling me what I need to look for in order to find a drive with corresponding/compatible enclosure?
You just need one that is a 2.5" SATA SSD. Any consumer 2.5" drive will be SATA. You are highly unlikely to come across any budget drive which is U.2 or SAS. Anyways just make sure it is SATA.
As for an enclosure. This
UGreen enclosure is a USB 3.1 Gen 2 option. Most USB C models are USB 3.1 Gen 1 or have lower average reviews. You could use it for an SSD or 2.5 HDD.
Yeah I have one of those for backup, but I need to get something for work files. I have an old Elements external HD that never gave me problems with my old Macbook. On this computer though, I dunno if it's old or if it's the USB C adaptor cable that makes it keep ejecting. If it's the cable, I'd go with HDD; if it's the drive I wonder if SSD is more future proof.
Probably isn't worth the time to figure out. Likely some communication issue. A new HDD in a modern enclosure will likely work fine.