Skull & Co. Skin, CQC and FPS Thumb Grips Joystick Cap Analog Stick Cover for Xbox Controller and ROG Xbox Ally- Black, Set of 6

https://a.co/d/0dY9UKgJ Amazon. Think you can get them on their own site as well.

https://a.co/d/07mwNepj These are the ones I bought. Comes with 3 different ones, I just like the feel of these ones the best.