I meant like politically speaking. Feels like her family would have destroyed the country as revenge long before the player could even reach any of the middling ends much less the secret prince good end. Also, gotta say, from an otome game perspective, it's very "I'm only playing this game to be a completionist" to put the true end behind a guy the player just met. Maybe the MC wasn't speedrunning the game. Maybe that's just how fast the romance has to go so the game length isn't doubled
I feel like your timeline is rather screwed up if you think the events (framed for false charges->exile->dragon'd) are so far apart for the player to have time to do other things.
Considering she make a quick return and her family was ALREADY wrecking havoc, there's a good chance the dragon attack happen in similar timing even in the OG, meaning there's almost no down time between that false crime->exile->final boss flow of things.
Also the crown prince is supposed to be unlocked much earlier to get the true ending (page 9)
So in the OG what likely happened is that:
Just like here, he's on the mission to take down the dragon.
Given the timing gap of the dragon appearing vs his attack trying to stop it here, in the OG he was likely too late to save villainess (maybe not even realize it was her, since even here it took a bit for him to know) but was there to witness the dragon power up and fly towards capital.
He'd rush back to protect the capital.
With max affection, he'd choose to protect heroine and slay the dragon first, then handle other stuffs afterward.
Without max affection he'd probably run into the rampaging villainess family, learn of what happened and put the pieces together and decide this is just karma for trash prince and focus on saving others/convincing the villainess family to stop their rampage (possibly by apologizing for being too slow to save her)