If you’re getting a mini PC then your NAS can be older and really underpowered since it’s literally just housing your HDDs and not running compute heavy tasks.

You might need a bit more horsepower if you want to use Immich AI and PaperlessNGX AI.

eBay has been great and secondhand tech is worth taking the (small) risk on for the big savings. Get an old NAS that still gets firmware updates. Synology has worked great for me since it handles reverse proxy safely without me trying to learn that myself and doing a bad job to leave my server exposed and vulnerable. Get a mini PC suitable for your needs. I got a 12th gen Intel one earlier this year for £230, many companies dump “old” stock that’s perfectly functional. Look out for which CPU has a good enough iGPU for your needs if you need something like Jellyfin video transcoding.