my creo is more in "road" mode most of the time, and the sum of things i've done are as follows:
1 saddle (didn't go super light though; currently on a s-works romin mirror, only saved around 30g but it feels great!!!)
2 carbon cranks - not a massive weight savings (116g in the sizes i used), but meaningful. the only ones that fit, afaik, are the praxis:
https://praxiscycles.com/product/carbon-m30-ecranks/
3 speedplay pedals - i have both a set of nano and zero, i'm a few lb above the weight limit for the nanos. i originally had very heavy pedals and shoes on mine, big difference.
4 replaced quick release axles with robert axle project through axles. 59g savings, looks way sleeker, less likely to get a wheel stolen randomly
5 roval terra clx wheels with gp5000 tires, tubeless (you've already done this too!) (400+g savings)
6 replaced chain ring with wolftooth (i do need climb gearing, so i went with a 42t, saved 30g)
7 replaced rear cassette - if you had the sunrace 11-42, that thing was HEAVY. i saved 190g and kept the 42 by going to an SRAM 10-42 cassette. there are also big savings in the driver
8 i replaced the stock "hover" bar and stock stem with a one piece roval cockpit. i just really like the way it looks and feels, probably not worth the $$$ objectively but it also saved over 200g from stock, in a place where you really feel it when turning or picking up the front end
the weight savings of all of the above is only around 3lb, but most of it is in rotating mass, plus reduced rolling resistance on the wheels and tires. it feels like a very different, much nimbler bike. as you know the wheels and tires are the biggest thing you can do. i have my original wheels set up with some 42mm knobbies for gravel, and it seriously feels like you have the brakes on a tiny bit all the time by comparison!
the next biggest "feel" difference was the cassette, and then getting rid of the heavy hover bar and corresponding stem. your bike may have come with a better one.
would love to hear what you find out about changing the rear mech - since i'm using a 10-42 i probably don't have any options but you should be able to go with something else.
for the ultimate in weight reduction on a creo... have your shop take the battery out and run with a range extender only! another 800g. depending on the the other choices you made could get the bike to just a hair under 25lb!!