No, we detect the remnants of these bursts that happened millions of years ago that are just now reaching us

If I recall correctly you have to remove the core, and you essentially have to refine it again, removing all the decay products, and then you have to reshape it because the geometry of the core is super critical, and then you put it back in.

I did a quick Google check and couldn't find anything. Doesn't mean it's not out there though.

The only thing I could find was in a recent NPR article stating that inspections were put on hold back in 2020 due to covid, so probably 2-3 years at the least. However nukes have a lot of finicky components that have to function perfectly within a very narrow time frame in order to achieve critical mass. These components require regular and expensive maintenance. You can't just put them in a hole and forget about them until you need them or they won't work.

The sun literally provides the energy for like 99.9% of all life on earth

Question, wasn't the reason Russia agreed to this initiative because otherwise we would have given the Ukrainian ships a military escort? If they back out what's to stop us from doing that now?

That's true, I forgot about that. That's why insects and other arthropods were bigger when the earth had a higher amount of O2 in the atmosphere and shrank when the O2 levels dropped.

Crocodiles sun bath, a lot. Body size is mostly dependent on how readily available food is. Crocodiles are big because their diet can afford it, they used to be bigger because the animals they preyed upon were bigger. It's not unheard of for large animals to go extinct when their food source begins to diminish (e.g. titana boa, megalodons, etc.)