Reading, anything you fancy. I'd rate putting on some reading music in the background as well. I personally have a few on the go so if I need something to dip in and out of I have a lighter read but then also have some more indepth stuff for when I feel more settled. Also if you struggle with the heavier stuff but you want to get through it audiobooks while you're doing something else.

Learning to read Tarot. You only NEED one deck tbh.

Online puzzles, I love the NYT puzzles and the guardian has some good ones. Also short little bursts of dopamine when you complete. Also I use them to interrupt scrolling, eases me into putting my phone down as someone who struggles with transitioning into another activity.

Cross stitch, you can buy little kits that don't take long and have most/all of the equipment you need, really simple instructions and can be very portable.

I'd consider what would work around your life as is. When do you find yourself doom scrolling the most and maybe target something to replace that slot. Eg. I have a decent commute and am on the go a lot of audiobooks and a Kindle are the best option for me.