@xadhoom I'm not too familiar with nextcloud or how it would fit in with this device. If you want a Raspberry Pi NAS for backing up and storing files on a home/small business network then I would strongly recommend OpenMediaVault and a device similar in hardware to mine. Then it just sits on the network as a network drive. Again RAID redundancy is available, really simple UI. That would protect you from most things except fire/theft.
Nextcloud seems to be the renter end of the service if my quick glance is correct. Can you host to Nextcloud?
I get there is a desire for as sleek as possible usability.
Once configured, this device in my guide needs little to no maintenance and just occasional monitoring. My next step is to integrate Sia-Cluster for it's sleek browser based monitoring for pricing and storage stats.