Your last paragraph describes the best outcome or at least the least worst outcome....Well, they wouldn't have started talking about sending military escorts if the Chinese military didn't threaten a military response. They wanted to just fly her there on a plane, have her vomit some words, then come back. Then China raised the stakes and said that the PLA could intervene to so not look soft, the US had to say their military would protect her flight and that's why there's a standoff for who backs down first. So it is symbolic; it just got bigger than what was originally imagined.
China doesn't want to fight now because the power dynamic is shifting towards China so future is better. The US doesn't want to fight because China is already strong enough with MAD ready but they know that the longer they wait, the worse it gets for them. It's like a guy in a room with a saw and an infected arm: he waits, he's gonna die; if he saws it off, it is unbelievably painful right now, and he could still fail or die from the new wound. If either China or the US had already decided to start a war, this is not how an intelligent country would ramp it up because this war between two nuclear powers needs no ramp up. Surprise all out nuclear blitz is the correct opening move if war is already decided.
For the record, I think if the talk on Thursday doesn't result in the visit being cancelled, Pelosi will land on Taiwan but her flight will be harrassed by the PLAAF and they might do armed flyovers right in the middle of her trip, as she talks in public, right over her head, maybe even load up the chaff compartments with little Chinese flags and dump them all over her. And all sides, PRC, ROC, USA will have orders to not fire unless fired upon.
There is zero chance the US will backdown or have the flight canceled.
As for MAD right out of the gate, thats certaintly an option US, Russia, China have etc but America still prefers to contain/guardrail the destruction to within Asia.... its still believes (naively) that it stands a good chance of winning and defeating China without its own homeland/cities getting glassed