There’s already a blurry line between what counts as a single word in Japanese. Some linguists treat something like 私の as two words, some treat it as one.
If you look in a dictionary, you will find lots of things that are kind of indisputably single words. For instance, 切る, to cut.
But in the dictionary, you’ll also find 切っても切れない, which literally means “even if you cut it, you can’t cut it.” In other words “inseparable.” In this case, it has basically become a long い adjective that looks like a phrase made from the て form, the particle も, and the negative potential form of 切る.
But it’s still probably best to think of it as a word in Japanese, because it comes as a set in this case.
But you could make similarly structured phrases from new combos which wouldn’t sound like words to Japanese people, because they’d be original to you.
生物 is definitely a single word… there’s no real way to consider breaking that up without losing information / changing meanings beyond recognition.