A patch job will never match with what you have there now.

Consider painting the entire deck with a non-skid paint.

Kelley Technical Coating's line of Olympic Patio Tones is easy to work with.

It's water based and has a variety of colors.Reasonably priced.

https://olympicpoolpaint.com/Products

We have used it in the past to spruce up old concrete decks.

Kool Deck doesn’t have a life span of 20+ years! We just had ours redone after 15, it needed it badly. They smooth everything down, level it all, replaster/concrete, stamp it, then repaint. It looks perfect and brand new, was approximately $5k for a pretty large pool deck.

Contact Mortex manufacturer, they use to sell repair kits, they probably still do. There is a toll-free number on the website give them a call.