For context, this is about the overall mood and underlying color of the setting.
I have always looked to the Holy Roman Empire as a potential analogue to the world-building in Dune given the Emperor+Landsraad continuum (granted, it borrows from a lot of places, of course).
I recently picked-up The Artist, the Philosopher, and the Warrior billed as “Da Vinci, Machiavelli, and Borgia and the world they shaped” and ran across this little gem:
“. . . in 1478 Florence witnessed a tumultuous event: Lorenzo the Magnificent (de’ Medici) just managed to survive an assassination attempt backed by the powerful Pazzi family, who had the covert support of Pope Sixtus IV in Rome.”
I never really considered Renaissance Italy. But, I will now!
My historical instincts always led me to Mediaeval Britain and France. Britain for the Landraad type elements and France for the glory of L’Empereur.
I can see both HRE and Renaissance Italy working well though. The political infighting amongst the Northern Italian city states could feed a dozen plots.
I was planning on having a House whose Primary Domain was staging plays and theatre. I feel a bit of Italian Baroque style coming on now… Yes, a Masque Ball. An assassination… An Operatic Tenor (who Everyone just wants to Go… )
I think Ezio helped there in the shadows…
(This really reminds me of Assassin’s Creed II, iirc, this is an actual mission in the game)
And, yeah, i think you could pull a few inspirations, but a few assets in Dune would need a change to fit this setting, specially the high tech ones…
Then I would really advise you to read The Accursed Kings books: https://en.wikipedia.org/wiki/The_Accursed_Kings
" American author George R. R. Martin called The Accursed Kings “the original game of thrones”, citing Druon’s novels as an inspiration for his own series *A Song of Ice and Fire."