My ROCK uses a 250GB NVMe drive…its a NUC7i7BNH now ROCK itself uses next to nothing for the CORE system, the database is currently running some 150,000 tracks and ROCK web screen is indicating 97% of 227 GB available. The RoonServer folder where the database is held is ~6.7GB
If you NUC with Opthane option is not installed with any OS yet then just get ROCK and give it a try.