Yes, you’d need to use something like LiteFS for best availability.
You can run with one volume just fine, we just want you to know that apps with one volume are more likely to fail than you might be used to. I run apps with a single volume pretty frequently, but only apps that won’t hurt too much if they go down for 15 minutes or so a couple of times per year.
There’s also a data durability issue. Our volumes are on individual physical disks. If the disk fails, you will lose data. You can restore from the previous day’s snapshot, but that’s still hours of data that may go missing. If you’re ok with that, it’s no big deal!