Indeed, it would be great to have something like this for non-business customers as well. Right now it's very much targeted at large businesses atm and seems to want a beefy computer, so you can't really install it on your RPI.

https://developers.facebook.com/docs/whatsapp/faq

> For single-instance production server setup, we recommend at least 250 GB SSD, 16 GB RAM, and 4 core CPU.

https://www.facebook.com/business/m/whatsapp/business-api/

> In order to ensure a high quality experience for businesses and users, we're in a limited public preview. If you'd like to work with us, submit more information about your business for consideration as we continue to expand our availability.

The beefy computer requirements are really just the result of needing to invent pie-in-the-sky specifications for the website, and wanting to avoid any bottlenecks when running at high load. Remember, most of the current customers are trying to actively communicate with an enormous number of contacts.

The truth is that the product does not actually need much RAM, and storage is a direct function of the number of conversations and messages you're handling with the product. The main bottleneck is really just I/O for the databases. For the use cases of everyone here, it absolutely could run on an RPi. Easily.

> Offering low-volume non-customer-facing free access to a product like this would likely make everyone here quite happy.

I suspect that one reason they're not doing that is to prevent spambots. This is probably a valid concern, as experience as shown that preventing spam is a hard problem.