Reference question: Is an atmosphere's oxygen partial pressure or concentration more biologically significant?
While discussing with the OP why they were looking for so much detail the OP said the following:
I'm making a fake scientific textbook/artbook, about how life might evolve on planets with different conditions. So it actually is important to me to get the science right. For most readers, it will be more of a coffee table art book, with the main point being the illustrations and the writing serving the aesthetic, giving the book legitimate textbook vibes. But I want the book to work on multiple levels and to be accurate for those interested in the science. So I really want the science to be actually plausible.
It's fake, but it's not fake. It's not an imaginary world of the OP's own creation, so to speak, but a scientifically factual/plausible book about what extraterrestrial life could be expected to be like in Real Life if we ever find it.
The OP is not an expert in the field of xenobiology or, I suspect, any related field. The OP is using us as surrogate experts to help with the creation of the book.
The Problem: The idea is fascinating and would likely be a lot of fun. Except that to meet my current understanding of what the OP is trying to achieve, every question asked should be assigned the hard-science tag. It would cross a fair number of scientific fields. But while there is speculation, there is no fiction. We're not helping the OP develop and consistently use rules for a world of his/her own creation. We're co-authoring a whimsical, but essentially factual textbook on interstellar life.
There's obviously a lot of wiggle room here, but the basic question needs to be asked:
Question: Is the effort to create a textbook (fake or not) based on scientific fact close enough to worlbuilding as defined in the Help Center that questions of this type are permissible?
This post is a result of my asking the OP why such precise detail was needed in his/her worlbuilding efforts. My interpretation of the OP's response is, "I'm not worldbuilding" (from the perspective of the Help Center's definitions). The purpose of this post is to discover if a balance can be found between what the OP will need to achieve his/her goals and what we really can do. I've mentioned to people before that we're not a free research service and we're not here to make up for years of unacquired education. The linked question combined with the OP's response suddenly makes it sound like the OP's hoping we're both of those.
Also, I'm a little worried about... let's call it "liability." We have amazing people on this Stack, but are we in the aggregate qualified to answer questions for this purpose such that the OP doesn't get laughed at by people who review the book? When someone reads fiction (OK, when most people read fiction) they understand that what they're reading isn't real and isn't purported to even be plausible. We enjoy scientific credibility in stories, but it's not a requirement. If mistakes or complete gloss-overs are encountered, they're ignored by suspending disbelief to enjoy the story. But that doesn't appear to be what's happening here. Done "correctly," every aspect of the proposed lifeforms and their biomes should be completely supported by current scientific understanding. We have respondents who ignore tags and who will answer anything — qualified to answer the question or not. Can we meet the OP's needs?
While I am concerned that we might not be capable of meeting the OP's hopes and expectations, I do not have a bias toward the community's willingness or not to accept an effort like this as worldbuilding. I'm asking because I didn't know how to respond to the OP's explanation.
I have invited the OP to contribute to this post so we have a better understanding of the issue.