Have you tried knitting or crochet?

It’s small, portable and as engaging or monotonous as you need it to be. If you use public transport to commute instead of spending time on social media you can knit/crochet it has so many benefits. you’re disengaging from a screen/computer (if that’s what you do for work/reduces chances of you checking work emails etc), the repetitive motion is soothing and you have something physical to show for the time on the commute.

You don’t even need to make “things” some people make clothes/hats/socks and gift or wear them. Some people just enjoy the process and can stitch up an entire ball of yarn, unwind it back into a ball and just start again.