It’s really not complicated. Look up Truenas or Rockstor. Both are solid NAS OSs. I’ve been running Rockstor for about a year now (partly because I’m a huge fan of btrfs) and I’m pretty happy with it. Make sure to keep an offline backup on an external drive just in case you mess something up. I manually plug in a drive about once a month for that. I think DIY is more fun anyway ;) and I’m sure the community will help with questions you can’t find answers to online. Good luck!

I’ll just say this: you get what you pay for. I used pCloud a few years ago and wasn’t able to retrieve all my data, some files got corrupted (luckily I had backups). Now I use a DIY NAS and backup to B2.