I tried GentooPlayer a while back on raspberry Pi, but haven’t used it for some time.
The other night I finally figured out how to SSH into it again and have it running headless, the Minim server app seems to scan the attached hard drive and I can see this as a server on the Nova.
It seemed to work well previously but is maybe 12-18 months out of date.
I haven’t used it myself for some time but the last version I used on RPi was very good. Gentoo itself is open source. The guy that maintains GentooPlayer has a license charge for its use/support and there are some restrictions around the license. Drop him a line re. the fail he’s very responsive.