I'm thinking that Apollo covered 90% of the useful spin-offs from developing tech for manned travel to the moon or Mars. And at least 90% of what's left was either covered by the ISS, or could be covered by a few small LEO space stations.

The economic cases for manned moon or Mars programs look really iffy these days. The US has poured tens of $billions down the SLS rat hole, with very little to show for it. And Wienersmith's A City on Mars is a pretty damning dissection of the whole concept of Martian colonies.