I may be misunderstanding what's being said here but as far as people saying it can only be used with edo tensei, you are under a fundamental misunderstanding of the technique itself. Based on the way the technique is shown and performed, the only, and I stress only thing the edo body is doing is providing the paper for the first 5 or so tags. The edo body is not producing the additional tags, the tags are producing additional tags. There is nothing stopping tobirama from just carrying five pre-marked tags with him at any time and performing this technique even without being edo tensei. In the instance it was used, yes, the only logical explanation for what he did was that he applied the seals at that instant to some of the paper his body was composed of, because obviously his edo tensei body isn't just some kind of container for ninja tools.
The most probable reason the explosion stopped was not because his body was exhausted as a raw material it was because Obito stopped it. The manga clearly shows Obito with a truth seeking ball construct out when the explosion clears, meaning he basically vaporized the tags to halt the explosion. Yes I'm aware that he didn't have jutsu negation at this point, but the normal disintegration of the tsb is more than enough to have stopped the tags. Literally the only advantage an edo tensei body provides is allowing the user to survive the explosion, though really there's nothing stopping someone like Tobirama from just using ftg to retreat to safety.
In regards to the seal itself, since Tobirama clearly showed he can apply it on the fly, there's no reason he shouldn't be able to apply it to other objects and targets besides tags, though I do feel like it should be mentioned that there is no precedence of an explosive seal being applied to anything other than tags. Honestly if it was possible it would make explosive tags in general vastly more broken than they already kind of are. It would help if we had any idea of how explosive tags work in general. Since it's never been explained whether the explosion is being summoned, if the seal is just charged with chakra to explode, or if the seal provides a charge and the paper tag itself serves as fuel, etc.
There are too many unknown factors in regards to how tags work, but it can safely be concluded based on what we saw that the jutsu is not ET-specific and the seals can be applied on the fly.
