My contribution is, if you're a strong power in the early game, no CB Byzantium as soon as you can and vassalize them. Then go about your normal plan till you can hit tech 6 super early, and smash the ottomans by returning all of Byzantium's cores. Effectively killing them, and neutralizing their threat.
There's a more efficient way to do this imo.
After no-CBing Byz, If you have the fleet, wait until the Ottomans move all their troops east to attack Candar/Dulkadir. As soon as you see them cross, and I mean the absolute second, move all your men to Constantinople, declare and barrage Gallipoli then assault. It often has no garrison (you can almost guarantee this by ensuring you have no men or boats in Constantinople) and you'll have it down instantly. If you see it has some garrison, as long as it is under 500, it's fine, but if it is more than that you may want to hire a merc company and make sure you have highest morale possible. The Ottomans won't attack as long as you have 24k + sitting on that fort.
Then you siege Edirne/Saloniki and carpet siege the rest of the Ottomans, and let ticking warscore ride up. That alone will be enough for 70% warscore (Byz cores + money or an extra province or two) but if you want more, do the usual thing of allowing smaller Ottoman stacks across the strait and then stack wipe them by temporarily unblocking the strait to give them the illusion they can cross again, then block it just before they cross for the easy wipe. That'll get you up to 85-90%. You can often peace out his ally too especially if it's Tunis or AQ since they might end up in another war.
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only thing you have to worry about is if either the Ottomans have allied Crimea or if Ottomans have already declared on Candar, who is allied to Crimea. The reason for this is he'll get military access around Crimea, but honestly the Crimean - Ottoman alliance doesn't happen too often and if you're quick Ottomans won't have declared on Candar yet.
Aragon or Venice are the best nations for this because they have the fleet, they just need a few extra cannons (I usually get 9 extra galleys for Aragon to totally wreck the Ottoman fleet. I'm way over the naval forcelimit but it is 100% worth it).
There are no allies needed, it's pretty reliable and the only RNG is that the Ottomans don't have a relation with Crimea. You can get this done by 1450 at the latest.
You could do it as Castile or France but for Castile, the stab hit is brutal, and the French fleet is 50/50 to beat Byzantium let alone the Ottomans.
This start as Aragon is one of the best starts in the game imo because you can expand east with ease.