How small are these devices? I think the other problem is that neither BTRFS nor zfs really are suitable for removable devices, and definitely not for ones smaller than probably 8Gb at the very least.

Unlike NTFS which is just a file system, both BTRFS and ZFS do volume management too, so it’s not just a single partition thing; they prefer to take over an entire volume and manage everything.

So while they’re the closest filesystem with NTFS-like transparent compression……they don’t match exactly.

I also hazard to guess if the devices you’re using are too small to accept a BTRFS formatted volume, no amount of compression is going to be enough to fit what you need.

If you just want to play with a bunch of small old devices……maybe play with LVM and small RAID arrays and configurations instead. You can the build a bigger volume out of a bunch of those disks together and then put a BTRFS or zfs volume on them. Can be fun to experiment and learn with anyway.

The equivalent would be either zfs or btrfs compression. Transparent to applications, you don’t have to do anything special other than enable it.