For mortgages, lenders will entirely or heavily discount RSUs for income calculations.

However not discouraged by that fact, some tech folks are known to instead have taken out regular non-mortgage variable rate loans with their RSUs as collateral. So there are folks, who bought a house "all cash" with loans backed by stock collateral that is now worth much less. Those types of loans also have a double-digit APR, which might have been fine if you thought you could flip your house for 30-100% in the near future. In the current housing marking it is like putting everything on black at a casino, it might work out, but it might be also be a complete catastrophe.