Another solution is running full Calibre under Ubuntu on a Andorid TV stick. Mine use MK802 model and store my Calibre library on Buffalo NAS Linkstation Live. You may use USB drive to store the library without using a more complicated NAS.
With this setup, it consumes only 4-5 watts, with wifi on all the time.
With VNC installed on the stick, I can control my stick remotely with any VNC viewer.
https://www.mobileread.com/forums/sho...d.php?t=202659
Performance wise, it is more than acceptable with over 3000 ebooks in the library.