My brother and I would like to have some sort of storage space in each others’ systems as an offsite backup thing. Ideally, I’d be able to allocate him 2GB of space that he can drop files in (e.g. a Veracrypt container, perhaps a keepass database, not media files). I don’t want him to be able to access anything else on my network, like my own computers when they’re switched on.

Is Nextcloud a solution? I’d like a sort of Dropbox-equivalent solution where I can just open up a bit of space to him without it being access to anything else. Assume he’s not a malicious actor, but also that I want my stuff to stay private.