They’ve stopped screwing around with the complicated bombs made out of “nuclear trash” and going for the simpler design made out of uranium.
For good reason, we tested the plutonium implosion “Fat Man” design but didn’t test the uranium gun “Little Boy” bomb prior to dropping them on Japan in WW2.
We tested the plutonium bomb only for a couple of reasons, we had more refined plutonium, and the gun-type uranium bomb had a much higher degree of confidence as it was so simple and stable. Agreed, the complexity of detonating an implosion type bomb has really stymied all who have tried.