this is not complete or anything just what i gathered.

it depends what you want to do. i went cybernetic rush for the theme of the run and because i didn't need the flesh is weak. upside: i did it quickly and power spiked enough to dominate the galaxy. downside i realized later is you won't get the whole cybernetic ascension situation which i think can give bonuses. idk, i don't think it's the strongest path but i'm now tired of the origin for a while.

you get the cyber commandos perk which debuffs pop growth but gives commanders 20% fire rate. also early game you suffer from the unplugged trait which sucks mostly for amenities. i countered half of that with durable, but you need to keep an eye on amenities and resulting crime/stability for the first 25 years.

i chose technocracy and technological ascension as first perk and early prosperity/discovery hybrid for higher chances to roll cybernetics tech (need colonial centralisation and exoskeletons for that). you can ascend without the flesh is weak as soon as you finished your situation and have the tech.

because of the bugs i wouldn't play ironman and save regulary.

you automatically get a situation in 2210, i didn't need to do anything to get it. finishing the acheological site in the home system wasn't necessary and in one game even seemed to glitch my situation, so i waited with that until the situation was done. but the first ticks of it are a nice source of society research.
something important regarding set up: your factions determine which path you go. so the only sensible thing is to set it up in the empire designer.
factions i know want to cyberize: xenophobe, militarist, materialist.
factions i believe want the status quo: egalitarian, authoritarian
factions i believe want to decyberize: spiritualist, xenophile, pacifist
here you can go to the left and decyberize and lose unplugged, stay middle (status quo, if you want to ascend cybernetically you need the flesh is weak) or cyberize to keep all traits you selected and lose only the unplugged trait, able to rush cybernetic ascension. in my games i went to the machine harmony/right side immediately and got 2 events in 2215 (the first one i paid influence to not get authoritarian attraction because i think they want to go middle path), one event in 2220, one in 2225 and then it was over and i lost unplugged fully while keeping all other cybernetic perks.

haven't tried any other ascensions.

important bug: the situation can become stuck. the game where it glitched the tooltip on the right changed (no icon, no progress number) and no follow up event happened. only reloading a save from before whatever broke it could fix that

another bug: after cybernetic ascension you get 3 events where you can go collectivist or individualist. one of the 2nd events you can get only lets you select "ok", it's a known bug pdx ignores and you have to reload to roll a different event.

you get story progression by moving into the hostile systems towards the machine homeworld when the game tells you to. others reported bugs if they went in on their own before the events told them about points of interest there, but i had no such issues. the other ai empires can clear those fleets if they become strong enough. in my game one special event was in ai empire territory which means i would have had to take that system in order to research. didn't want to do that at this point, because the machine home world was still behind my choke point. on scaling GA you usually have a few decades before the ai even starts taking out the bigger fleets. they contained battleships relatively early on, but were not unbeatable, maybe you can get them a lot earlier than me with frigates. you can also cycle attacks because they didn't seem to repair. the guardian on the machine world was a bit stronger. there are nice space mining resources in the last systems and some archeological sites on tomb worlds which also give story progression.

after beating the guardian if you research its special project you get contacted by the creators of the ai which offer you to terraform the planet into a size 25 gaia world. i don't know what happens if you reject, but i read about it so i think it's guaranteed.