Full Wings:
If you have access to a 777 FCTM you will find that postive climb is NOT called with reference to the VSI or radalt but solely with reference to the altimeter.
Yes, that’s what we do but some airlines have different SOPs. FCOM > FCTM.
The VSI can and will show positive climb when the gear is on the ground because it is only a measure of acceleration.
You can get it on up-sloping runways, too. It’s small effect but if you lost an engine at MTOW you might not be expecting much of a climb rate to begin with...