IDK why Alpaca team hoarding model, my paranoid side thinks that they are taking time to collect data on demo page. xD
Alpaca is a fine-tuned version of the LLaMa model - so if they release Alpaca they're essentially releasing a version of LLaMa, which they aren't sure if facebook is okay with so they're reportedly waiting for their permission.
While yes you can easily find LLaMa it's technically not intended for the public according to Facebook.