For t shirts I always sing the praises of Gettees. Tiny “factory” of half a dozen people making extraordinarily high quality and durable shirts in Detroit. Most of the people doing the sewing are former auto upholstery stitchers from the car factories. The quality is truly the best I’ve ever encountered. https://gettees.us/
You can add pockets to the pants you buy, too. This video by Morgan Donner is adding several examples of types of pockets to skirts, but the process is the same. https://www.youtube.com/watch?v=7pE_nrHKd58
And there’s this one by Bernadette Banner https://www.youtube.com/watch?v=thlzJj1EHiY
Thigh pockets are really great for phones. You can make visible patch pockets or subtle welt pockets and you can customize to the size of your phone.