Nope, there's nothing in to movie to tell you there's an easier way.
Now point to the part that says that can be done from inside the Death Star.Because we know exactly what will set off the chain reaction: any explosion in the main reactor.
"the reactor module, that's the key. That's the place I've laid my trap. It's well hidden and unstable, one blast to any part of it will destroy the entire station. You'll need the plans, the structural plans for the Death Star to find the reactor. I know there's a complete engineering archive in the data vault at the Citadel Tower on Scarif. Any pressurized explosion to the reactor module will set off a chain reaction that will destroy the entire station..."
And that would be a whole lot easier to accomplish if you are inside the Death Star with some explosive charges than outside it in an X-Wing.
The only reason there's a ticking clock situation is because people are planet side to coordinating the attack.What about "they are on the clock" do you not get?
They don't have time to infiltrate the Death Star before it blows up Yavin IV.
There isn't anything in either movie that tells you it's even possible to attack what they need to attack by means of infiltrate. This is just something you're assuming based on nothing in either of the films. You weirdly keep bring this up, but it's not a thing in the movies, it's just an alternative way you've imagined it could be done. If they wanted to give you the impression there were multiple ways for them to reach the reactor in Star Wars, but they were going with what they were because of time, they could have easily done so during that briefing scene...but they don't. The movie only gives you the impression there's one way of doing it, and that's the way they do it. This movie just tells you the way they did it was actually secretly hidden there to help them all along.
The gas giant?Now, for a really big plot hole, why didn't the Empire just blow up the planet Yavin IV was orbiting instead of spending half an hour going around it?
What in the film gives you the impression it wasn't? Han left and came back before the Death Star was even in attack range. What makes you think they couldn't have abandoned the base earlier?What in the film gives you the impression that evacuation was an option?