Finish the top layer with a gel coat repair kit mixed with pigments to match the existing colour. Use old fashioned glazing putty to copy the deck structure from an undamaged part to the still wet gel coat.
My experience is that the colour is very hard to match on old boats that have been subjected to UV. In that case there is always the solution to paint the whole deck with two pot paint after the repairs are done. One pot paint could be used (easier to apply) on spots that are not mechanically stressed (walked over), but you certainly don’t want two sorts of paint on the same deck. So, stick top two pot paint.