2×9 isn’t really much different to 2×10. The main upgrade there is just clutch mechs, which are nice to have but not really gamechanging… 1x has bigger differences but at the end of the day it’s not going to change the bike’s agility, it could save some weight but will that do what you want?
I ride a Big Honkin 29er as my main bike and I think wheels and tyres are pretty important, if yours has heavy wheels on it now I think that’ll be the biggest change.
Bars are good to mess with, it won’t necessarily make it more nimble- that means all sorts of different things to different people- but tweaking controls will always change how you fit on and interact with the bike. And it’s pretty cheap, too, you can get bars for buttons and try different lengths (stems, too, remember- they’re pretty much a package)