I remember the sieges by Perturabo vs the orks that repelled both the SW and WS (probably because neither of them spoke gothic), Dantioch vs Idriss Krendl the inventor of the Ironfire, Kyr Vhalen's and his buff to sieges, even when anon pulled a Paramar inspired by his actions...
But all the siege we know of the IFs are two bits: Dorn becomin Praetorian for some fucking obscure reason that is NEVER mentioned and doesn't even discuss the specifics of fortifying Terra but insteads uses the Fist's bigger than average fleet to hold the Solar system...and a bit about fists building a fortress on each world they conquered. Singular fortress.
Oh you think that's an innovation? That's standard procedure.
The Fortress of Compliance built on Istvaan III that survived an exterminaturs and from where Tarvitz fucked Eidolon's army? Built by human hands: that world was conquered by the Raven Guard.
Despite supposedly their siege-y nature, we have no accounts about Imperial Fists even being on sieges besides the Battle of Terra and the 40k Sentinels of Terra supplement, where they're confused with the Black Templars.
In fact that's all we do know from the Fists:
How Black Templars are the only ones who aren't famous for geting BTFOd (OG Fists, Crimson Fists, Soul Drinkers, the other descendants aren't even famous at all), how they're good with shooting rifles and how they have a good fleet and are good at boarding, as seen at Phall.
At Phall they also launch three known boarding attacks, two of them fail.
But yeah, Imperial Fist sieges. I'm still waiting for them.