What about audiobooks, discord/slack for team communication, or sometimes reading on public transport. You can easily block/mute notifications and all that. Don't use apps like Instagram (never used but some of my friends do) or other addictive apps and you'll be fine. To be honest smartphones are you the best way to push some (25 minutes) to practice skills when you have time window (apps like brilliant, Reedy)
Phone game apps are the most addictive but if you never download them you won't get into it. Games have 4 caracteristics that makes them addictive: winnable, it has goals, novel challenge that keep you in state of flow, feedback. These things could also be used in reading books and that becomes addictive in a good way.
Tl;Dr phone apps are the best thing to aquaire skills in the future. If you block or hide notification and not download addictive apps you will be fine.