The main problem with such scenarios is they usually rest on Antony and Cleopatra winning Actium and…they just can’t. At all.
True, it's pretty annoying how unoriginal they are at that
Im trying to deviate from it with my TL having a much earlier POD
And they knew it, which is why they made a run for it and left Antony’s army to surrender.
To be fair didnt Egypt have a pretty massive navy? I've heard they
potentially could overwhelm Octavian's if Cleopatra didnt run off, the main issue being that Agripa made their navy a perfect counter to Egypt's with his much more mobile and hard to hit ships, so bare minimum you'd have to get rid of him
Spain is doomed no matter what. It does not matter if any of the Colonialist reform plans of Jose Galvez, Unionists of Floridablanca, Autonomists of Aranda or Godoy are in process, none will be applied and Spain will be invaded.
On top of that, for reasons no one understands, everyone in the universe (even the Spaniards themselves in the most egregious examples) agrees that Spain "deserved it", so "this is karmic retribution" (in a time when karma was unknown in Europe) and "the world is much better now" (even if the British Empire, USA and Germany have gotten drunk on their bullshit "white protestant superior race" rhetoric and are exterminating anyone who is not Protestant or "white enough")
It's weird also that Spain is always turned into THE Evil Empire in most post-1500s TLs
"Oh but empire always bad" sure, but the Spanish Empire was built clandestinely(Cortez, Pizarro, all outlaws who avoided justice by saying "but I conquered this tho") and the Crown itself had no desire for a conquest of America, only for converted vassals in the New World
But no, Spain is doomed to be
the super oppressive european empire
Meanwhile if the colonization is conducted by say Al-Andalus then its all good & nice with Islamic Iberia only doing trading and having converted vassals(which is what christian Spain wanted!) and if the evil empire is british instead then they surely can reform into a benevolent Commonwealth/Imperial Federation, no questions asked