Poland and Estonia, ended up much better off than those that chose a gradual approach, like Bulgaria and Ukraine
The main reason of the hardness of the crash of Ukrainian is the large share of advanced defense industry (which almost ceased to exist) in the GDP in 1990, as well as advanced civilian industries which were reliant on their partners in other Soviet republics. Belarus, which had similar economy structure but smaller share of defense industry in particular, which maintained economic ties to Russia and which implemented even less reforms and even more gradually than Ukraine, weathered better in the 1990s and might provide a counterexample to this thesis (even if the end point long-term is awful).
Also, both Bulgaria and Ukraine are further from rich Western/Northern European markets. Poland in particular borders Germany, which provides all kinds of benefits. Even then, Polish and Bulgarian GDP per capita were similar at the moment of their EU ascension (2004 and 2007 respectively). I do not exclude that Bulgaria had their own self-inflicted problems but you have to compare against Romania and Hungary to demonstrate that!
Does this count? A new mathematical result, particularly a proof of what a professional mathematician was intuitively sure of, but only a small part of an actual paper (literally just one proposition), and also took some prompt engineering https://x.com/bremen79/status/1927768299271496008