That's cool! I can imagine that being comfortable/fun to use... Extended. The joycon analog sticks are so focken short ya know? So short and meh feeling... They get loose easily.
It’s a rubber thumb grip to increase the analog stick to make movements more precise and fluid. It feels a little unwieldy at first but it’s easy to get used to. I bought a set of them from China for like one dollar. It took a month tho until they came