So, capitalism then.

You don’t have to have anything particularly special. I just have nextcloud via yunohost on a raspberry pi. It’s apparently possible to just plug the harddrive in and use it as external storage, but I’ve mounted it in place of my home folder.

A bit of unsolicited advice now you’re in to tinkering. Set up some kind of NAS.

Having everything available wherever and whenever you need it is so much better than messing about with thumb drives.