>The midway point in the sea level tool you linked is actually 1.41m by 2100.

No. Not sure where 1.41m is coming from. Take a closer look at the linked NASA site. You will need to click on the link labled "View global projection" (sorry, there isn't a direct link). You will see a graph labeled "Projected Sea-Level Rise Under Different SSP Scenarios". The midpoint highest rise of all seven of the scenarios for 2100 is just .88 meters and that's for the most pessimistic SSP5-8.5 Low Confidence scenario. The more likely scenarios are about 1-2 feet.

Your great-grandkids will be fine.