Hydrogen doesn't buy you that much additional lifting power.

Air is about 1.2kg/m^3 at STP, so that's the theoretical maximum you can lift with a cubic meter of gas bag. (And you can only get that value if you could somehow hold a vacuum, of course.)

Hydrogen is about 0.09kg/m^3 at STP, so you can lift about 1.1kg/m^3. Helium is about 0.18kg/m^3, so you can lift about 1kg/m^3. Helium is twice as dense, but that only costs you about 10% of your lifting power since both are so light compared to air.

I see no reason you couldn't use hydrogen, but I don't know if anyone would want to take the risk. (Specific flaws of the Hindenburg aside, hydrogen is explosive across a distressingly wide range of mixture ratios with air.) If you did use hydrogen, I think the main motivation would be avoiding the use of scarce helium, not the minor increase in lift capacity.

If it's an unmanned drone-blimp, the safety issue because somewhat less critical.

But still critical enough to make it impractical. How would you do maintenance on a hydrogen airship without risking the people doing the maintenance? And you'd never be able to fly over populated areas.

It is possible but we all know what happened to the Hindenburg. Using hydrogen is asking for a fire to happen.

https://en.m.wikipedia.org/wiki/Hindenburg_disaster

Keep in mind that the Hindenburg was supposed to be helium filled, but due to import restrictions they couldn't get enough.

Far more helium airships have wrecked than hydrogen airships, even counting only before the Hindenburg.

Wrecked, yes, but they probably didn't burn like a torch with people jumping out of them to avoid burning alive.

What you saw was the engine-fuel burning on the ground; the hydrogen went straight up in flames and burnt no-one.

Vacuum still has the best lifting power of them all..

We just need a material as light as a balloon but rigid enough to hold its shape and maintain a huge vacuum at 1 atmosphere outside pressure.

Perhaps graphene aerogel, with a nonpermeable graphene casing?

I'm not sure of what its behavior would be with all its air sucked out, though.

like a hair full of nothing..