I'm not who you asked but Synology is pretty nice. Runs Docker nicely and lots of applications available for it. Recommend an Intel CPU based vs the ARM based Synology NAS systems. I use it to run various software for my home network.
Synology's ARM line is generally underpowered compared to their Intel offerings, in terms of clock speed, memory capacity, and core count. They also tend to gate additional features (e.g. hardware-accelerated encryption) behind their Intel offerings.
edit: We're mostly talking Atoms / Celerons here, so not exactly screaming performance either way.
There are third-party package managers for the ARM devices but there are a lot of broken packages so I wouldn't recommend using it.