Re DAS: no you can’t connect multiple systems to it. iSCSI and NFS on a SAN or NAS support multiple connections but the OS or app needs to support it.
You should limit your connections to one machine per volume when using iSCSI or nfs. Smb would probably the best for multiple connections.
Raspberry pi can handle a lot of those tasks fine and others slowly. They are dirt cheap and need very little space. You can add usb storage easily.
I would start there until you know what you’re doing and know what you want.