You need a phone for setup. Ranges, sampling, logging interval etc. And for starting up logging to microsd-card. After that, you could disconnect and let the mooshimeter do its thing.
I’m a bit paranoid about crashes and would not leave my mooshimeters unattended for much over a day, but i have had two mooshimeters logging total electrical consumption of my house for 10 days now with daily bluetooth downloads of logs. Everything seems to work just like expected. Both are on 1 minute logging intervals, but still, surprisingly stable results.
Off topic.. I have three 30A/1V current transformers connected to voltage/aux-voltage channels and as i still had one channel available, i hooked it to one of the 230V lines. Day worth of data graphs nicely on libreoffice calc (or excel), but week is hard to do so that it is easily readable.