Very interesting seeing how low the record has gotten. Good luck with getting a sub 2:38 if you're still trying.
Def have explored here and there, still can't find anything viable to get there. Without a TAS (tool assisted speedrun) I do not think sub 2:38 will be found any time soon without brute forcing every possible option. The big thing holding the record back is scrolling the upgrades. Because only so many can be displayed at once no matter the device deminsions, scrolling is needed for certain upgrades. This scrolling holds back being able to do any possible combination without sacrificing time. I'm sure there is some way to get sub 2:38 but 2:38 isn't consistent even with the current route. I find I get more 2:39s with the WR route which means the 2:38 was most likely the best time with the current route.