Every person taking equity needs to justify their value now
This means that a setup with two "business people" founders need to justify their worth immediately. Not with promises of future sales. Not with vague research.
Worthy ways to prove their worth could be raising a giant amount of funding, or putting their own money into the startup as a sign of skin-in-the-game, or purchase orders standing ready to purchase the product once it is complete, or paid PoCs. Or serious track record of delivery/wins.
If you find a setup where engineers are taking all the initial risk while "business founders" stay on the sidelines waiting for a product to be built until they start to work -- run away. Think about it this way -- they have all the upside (they can choose later to work or to flee) while you have all the risk (you invested your pay-cut for vague promises of future work.)