Pocket extensions are a great beginner’s sewing project, nobody can see your pockets in most pants so it doesn’t matter if your stitches are uneven. A basic sewing kit is all you need, you don’t even need a sewing machine.
https://youtu.be/LRAz9eQexHQ?si=m2RiNH1acfhkXTYM
https://www.instructables.com/How-to-Extend-Your-Pants-Pockets/
Paper tea bags usually contain polypropylene or another plastic so they can be heat sealed shut. They aren’t fully compostable.