Some composites can be slippery, but one of the most common complaints I hear about them is that they get too hot to walk on in bare feet.

I'd recommend a tropical hardwood over composite or pressure-treated wood. A species like Cumaru, Tigerwood, Massaranduba, Garapa, or Ipe. These woods are dense enough to avoid splinters, and have some natural anti-slip properties. They're also strong enough to last for decades with hardly any maintenance, as long as you don't mind the deck turning gray.

https://www.advantagelumber.com/wood-decking.htm

Ipe:

Chic California Decks & Patios · More Info

Garapa:

Gorgeous Garapa Decking · More Info

Grayed Out:

Resort Style Ipe Deck and Pool · More Info

Massaranduba:

Advantage Massaranduba™ · More Info