I designed thumbsticks for the Ayn Odin 2 that fit the Skull & Co PS5 joystick caps (link below). This is the 10th iteration and they have a snug fit and flat design on the top to fit the skull & Co caps.
Skull & Co thumbstick PS5 caps - https://www.amazon.com/dp/B079811C49?psc=1&ref=ppx_yo2ov_dt_b_product_details
Nintendo Switch cap version available as well: https://makerworld.com/en/models/252135#profileId-268478