512MB of ram might actually be too small for an OS and ZFS. It might work, but it'd be tight. Or you could see how BTRFS runs. I've not touched BTRFS at all.
I have actually thought about "what about just using USB flash drives on a pi with ZFS" before but every time I mess with a pi I run into weird, annoying pi or ARM specific issues. And they're also spectacularly slow compared to even the cheapest Little Guy (8 year old office PC)
Basically, you're going to run into more problems that need to solve because of your hardware. So while it would be an interesting project, I would not trust any data on it without extensive testing. And, again, even if it all works, it's going to be slow.
If you wanted to look up more, I'd be looking at the official documentation for OpenZFS and/or BTRFS and going from there. Since most of what you're doing would be "set up this modern filesystem on my pi" and then maybe "set up a network share on my pi".