Second this route.
Since OP wants to replace the “cloud”, which is a loose term but I take in this case to mean one of the Drive or Dropbox services, this would be the most direct replacement.
You’ll still want a NAS or otherwise storage focused server to host it, so you can get or build a NAS first. Use basic protocols like CIFS/SMB,NFS, and/or SFTP at first, and if that doesn’t meet your needs (say if there’s a mobile phone involved) you can go down the path of installing Nextcloud on it for that Dropbox like experience.
That said, this will move responsibility for two important things onto yourself. Failure tolerance and security. The corpus can afford automatic redundancy and failover, and backups going back further than they would like to admit to you. They can still lose your things to some mistake or another, but a dead hard drive generally isn’t one.
For backups, however much storage you want, plan to have extra drives for backups, and have a backup plan in place. If the data is important to you, you will want to be able to survive a hard drive inevitably failing, or a virus or even just a garden variety mistake. It can also be useful to ensure an (encrypted) copy is somewhere else, like a parent’s house or a locking cabinet at an office job. Having two copies at home won’t save you from thieves or a fire, after all.
And security. Don’t expose a NAS to the internet. Just don’t. It sounds convenient until some bug lets a botnet ransomware all your memories and you’ve got to scrub everything and restore the backup, losing anything since the last backup. Instead prepare to learn about setting up a VPN, and granting yourself an encrypted and well secured tunnel for your devices abroad.
All in all, it can be a worthy endeavor, but one that must be taken with care. Files can be important, and I would hate to be the one that offhandedly sent you down a path of losing your data. Learn, plan, and implement with confidence and a backup plan.
The good ol’ Red Scare.