The amount of fuel at the destination doesn't change the rocket equation for being able to get into orbit from the planet. From the provided link:

"If the radius of our planet were larger, there could be a point at which an Earth escaping rocket could not be built. <snip> That radius would be about 9680 kilometers (Earth is 6670 km). If our planet was 50% larger in diameter, we would not be able to venture into space, at least using rockets for transport."

If it's chemical propulsion, you're dead when you get there. If there's no refuelling (and you need refuelling) with some other travel mechanism, you can't get back.

So we have an "or" assumption, not "and", with an additional and assumption about refuelling. That's how I read it.

I think what the GP refers to is that there isn’t enough energy in chemical rockets to overcome its gravity, even flight might not be even possible albeit that’s also dependent on the density of the atmosphere to some extent.

Flight would actually be easier on such a planet. The advantage of increased atmospheric density is greater than the downside of the increased gravity.

That is of the atmospheric density is higher, we don’t know the composition and temperature don’t forget that at higher pressures the boiling point of water is higher so it might not actually have water vapor in the atmosphere.

The atmosphere can also be much more shallow than earth.

Also I was more referring to winged flight than balloons balloons might be a problem of their own if the pressure at ground level is too high for them to inflate normally.

Between earth and Venus there are a lot of options so if the atmosphere is similar to earths sans the water vapor I’m not entirely sure flight would be actually easier I can probably do some napkin maths over the weekend for this.

So... if one made a very aerodynamic craft, and launched at a more extreme lateral angle, do you think it would supplement the chemical rockets enough that escape would be possible?

not really going to orbit is about velocity not altitude the gravity at low earth orbit is pretty much the same as at sea level.

The savings you get when launching from say an aircraft at 40,000 feet mainly come from not having to go through max-q at sea level the relative amount of propellant you’ll need to get to orbit is the same you can just use a smaller rocket but it doesn’t help to overcome the rocket equation trap.

But at altitude you do get higher ISP, which is a greater limiting factor than drag/max-Q. The Saturn-V would not even get off the pad in an even slightly denser atmosphere. But lift it up to where the air is thinner, where its engines can generate more thrust, and it might have enough DeltaV to get something into an orbit.