I have made that migration myself going from a Raspberry PI 4 to a n100 based NAS. It was 10 minutes for the software stack as you said This not taking into account media migration which was done on the background over a few hours on WiFi (I had everything on an external hard drive at the time).

That last part is the only thing I would change about my self hosting solution. Yes, the NAS has a nice form factor, is power efficient and has so far been very optimal for my needs (no lag like rpi4), however I have seen they don’t really sell motherboard or parts to repair them. They want you to replace it with another one. Reason 2 on the same is vendor lock in. Depending on the options you select when creating the storage groups/pools (whatever they are called), you could be stuck needing to get something from the same vendor to read your data if the device stops working but the disks are salvageable. Reason 3 is they’ve had security incidents so a lot of the “features” I would not recommend using ever to avoid exposing your data to ransomware over the internet. I don’t trust their competitors either. I know how commercial software is made with the smallest amount of care for security best practices.