And if you do, why not just use Google Forms?
I also plan to add pre-defined layouts to the form builder which people can choose from and also more HTML/CSS (and potentially JS functionality) that people can integrate into their form without having to write code, which I don't believe is something Google Forms offers
You can host custom forms from Sheets with GScript. It's basically JavaScript and you can do a whole ton with it beyond just forms. You can even host websites from Sheets (as of 5+ years ago)