Use Umbrel as a NAS/Homelab

Hi, I bought a mini pc, I want to use it as a NAS/Homlab server, to run Nextcloud with my disks, and some dockers app. By searching, I reminded of Umbrel, for the UI, I'm really interested in that. I want to know, if it's possible to use Umbrel as a NAS, and use the storage in apps. I have 2 HDD of 4Tb and 8Tb, that I wanna plug with USB3.0 (waiting for a special dock with USB-C). I would like to know if it's possible, and if it's possible, to merge the two disks, like one? On ubuntu I use merge_disk, maybe there's something like that. Thanks for your time.