Funny how helium is smaller than hydrogen when it has 2 protons and 2 neutrons? Against hydrogen that is merely a single proton with an electron. Physics is weird sometimes. Although the explanation is simple that the 2 protons draw the 2 electrons closer, making the electron “shell” smaller.

But maybe this “size” isn’t universal, maybe Hydrogen can squeeze more under pressure?

Google gives me this answer to the question “is hydrogen easier to contain than helium”:

No, hydrogen is not easier to contain than helium. Hydrogen is harder to contain because its smaller, lighter molecules escape through materials faster than helium

So apparently hydrogen remains the more permeable gas, and hydrogen is also chemically very active, corroding nearly everything it comes in contact with.

Edit:
I figured it out, hydrogen is more permeable because it can interact chemically, making the electron shell near irrelevant.