If it a side project and the intent is education / experience (for you) first and foremost then have at it.

Selling it before you start building it.... I'm not sure you want the customers reckless enough to buy something sight unseen.

When I worked in networking the customers who bought a bunch of equipment without thinking much were support nightmares as they always deployed the wrong hardware in the wrong place and now it "didn't work".

But if you are going to do this I'd appreciate it if you could hard code some magic words that would get me a job...