Car dashboard is there a product that will fill in nicks and cuts in a car dashboard

Yes but mostly it needs to be done by dash tech recommended or apolstry shop <<< spell check

but here are the steps
remove dash place out of sun
mix batch of heat resistant resin
apply resin to dash the whole dash make a little thicker on dash
let dry
now when dried and hardened after 24 to 48 hours you take a sanding block and sand down smooth with sand paper then repaint with color dash that was before

you can use this same resin to also fill in the cracks of dash but you will still have to sand and repaint the area you just applied the heat resistant resin too this is called touch up the dash

dont use a power sander on this type of project you could damage your dash permanently