I would not consider language nor writing discoveries though.

Why are you pointing your weapon at random galena for the sustained periods that would smelt out metals?
Because I’m a grad student left alone with the scientific apparatus, and so are my friends. They would figure out that metal can be smelted from rocks in much the same way that humans figured out the biofluorescence of platypuses.
Hold up: Ima email Becky Chambers.

Because it makes the rocks toasty warm to bask upon when weather turns chilly
How do you make it to the point of breeding these sun-flowers if you need that kind of protection from the elements in the first place? But sure - there’s a huge difference between “toasty” and “red-hot”, and you have to take it past the latter to smelt. Why would you do that?

And then it’s used to make food taste better.
Thousands of degrees of heat (otherwise, it’s a useless weapon against your enemies) is only going to make your food taste like pure carbon. Because that’s what will be left of it.

And then it sets some stuff on fire
And now you’ve invented fire and are no longer “without fire”.

But let’s say there’s no combustible material available
I thought the whole point of the weapon was to point it at some ambulatory combustibles…

If you could use genetic manipulation to modify species to your purpose then you undoubtedly have technology.
That’s kind of my point. You can’t do genetic manipulation without hard science tech. The kind that needs fire, to make the materials you need to do the science. You’re not going to be breeding microscopes.

Because I’m a grad student left alone with the scientific apparatus
Why would you have science, if you don’t have technology? If all you do is breed animals and plants, you’re not going to develop science.

They would figure out that metal can be smelted from rocks in much the same way that humans figured out the biofluorescence of platypuses.
Smelting is way more of a process than just shining a UV light on something.

Why would you have science, if you don’t have technology? If all you do is breed animals and plants, you’re not going to develop science.
Again, I think you’re basing far too much on human cognitive patterns, and not allowing for things working very differently in a different species. And “all you do” is quite an oversimplification of the science-fiction premise here.

Smelting is way more of a process than just shining a UV light on something.
Well, yes. It’s also way more of a process than just putting a rock in an oven, but that’s likely how early humans first noticed molten metal.

Again, I think you’re basing far too much on human cognitive patterns, and not allowing for things working very differently in a different species.
It’s not about cognitive patterns, it’s about simple progression. Chain-of-discovery stuff.

And “all you do” is quite an oversimplification of the science-fiction premise here.
There’s a line between science fiction and science fantasy, and selective-breeding the telescopes and lab analysis equipment you’d need to do actual genetic manipulation (without a need for those things absent that) is on the fantasy science of that line.

just putting a rock in an oven, but that’s likely how early humans first noticed molten metal.
Putting a rock in an oven to do other useful things with is the important bit. And “an oven” is underselling it - most informed conjectures center around full-on kilns, like ceramic or calcining kilns. Those get way hotter than mere bread ovens or the circle of rocks around a fire.