It doesn't matter if some of the group differences are genetic in origin, given that others are not, we can still resolve those.

Those can be resolved but they will not make nearly as large a difference as currently expected, where current ideologies hold that all of that 3-190x per capita difference is due to environmental conditions, history, and racism. HBD implies that, just as with individual differences and the systematic failure of welfare and education randomized experiments to 'close the gap', we can expect this futility to occur on a country-level basis at some level of development. Countries like China (maybe) and North Korea (definitely) will be predicted to escape their current poverty levels with appropriate interventions... and countries like Subsaharan Africa to possibly not escape. (Which countries can be made more concrete in a HBD context by taking Piffer's country/group-level polygenic scores and looking at the residuals of a GDP/score regression for the countries which most over and underperform; the former can be predicted to not grow substantially, and the latter can be predicted to grow substantially.)

Remember how heritability works. If environments improve, genetics will explain more and more of variance. It's Liebig's barrel. Shared-environment in the USA is very small.

Do the implications here change?

Yes, because those environmental factors are causally downstream and cannot be improved without the locals. As development aid has discovered again and again, you cannot force improvements on a country. Pakistan, for example, is so dysfunctional and clannish that iodization and polio programs have had serious trouble making any headway.

The steps we should take don't depend on HBD being true or false.

Yes, they do! These causal models are fundamentally different. If genetics is a major limiting factor, iodine and all other environmental factors are not going to help past a certain level of development. (You can feed some Americans or New Zealanders iodine supplements, but it won't give them +10 IQ points even though they are probably somewhat deficient). If genetics is the major limiting factor, then at a certain point, you are basically polishing a turd and this can either be accepted or more radical interventions must be considered.