I built my own nas back in the day and it is not worth it. trying to remember an the mdadm commands, setting up Cron jobs for scrubbing and smart tests, setting up email notifications if the tests fail, flashing the firmware on my hba, setting up dynamic DNS, fail2ban (later a private key whitelist), borg etc etc. it’s not too bad if you’re an experienced Linux user but it’s still a lot of time out of your day, meanwhile if you’re a new Linux user then you’re basically just playing russian roulette with your data. building a jellyfin server is a good learning experience but for a nas I would pick an off the shelf appliance every time