I have a small ubuntu server running on a rockpi 4, I use it for everyday services like rss feeds (miniflux) and media (jellyfin). The only way I have found so far to be more resource efficient is to download movies and shows at lower resolution, this can reduce used bandwidth to a tenth. What other ways are there to save power and bandwitdth for everyday tasks?
That’s already a very low power solution. If you have external storage connected there might be still some saving potential, 3.5" HDDs use quite a bit of power, so do high end NVMe drives.
Software wise… maybe check the crons and reduce the frequency? Like your RSS feed reader probably doesn’t need to check every 5 minutes or so for new entries.