The short version
Nanocorp is built for speed of experiment. One sentence becomes a working business with a site, a database, payments, and agents that prospect and advertise. That's useful when you want to find out whether an idea earns anything at all.
Crevio is built for the business once it does. Payments go to your own Stripe account, the fee on sales is 1% to 5% rather than 20%, and the checkout, courses, memberships, bookings, and marketing are ready for real customers.
Which one should you pick?
If you want to test a handful of software ideas cheaply, Nanocorp is a fast way to do it. If you're selling to people now and want to keep more of what they pay, pick Crevio.