From experience, part time / contractors for early stage startups are usually counterproductive. They just won’t be committed, loyal, and giving 120%, while incurring massive management overhead. Don’t believe I’ve ever seen a success story.

Proper full time employees or don’t hire at all.

I think the opposite. I've experienced a startup with fractional execs, like fCTO, among first hires. They provide strategic value , motivated.

Then a contractors or devs shops for implementing. Those are not as motivated, thus execs will oversee it.

it is the cheapest and fastest option to validate product idea