I’ve used a couple types of fiberglass resin which have worked great. Create the texture with a popsicle stick and sand down any high spots. Paint and you’re gtg. I’ve also experimented with adding sand into the mix to give even more grip.
I’ll be putting together a complete stock finishing DIY within the next couple weeks if you want to hold out and see if it’s something you think you can handle. The texturing is very easy with the proper equipment.