I already knew the very basic N5 grammar when I started Bunpro so I only skimmed through a few of the sources to refresh my memory.
A complete beginner should definitely read through some of the grammar resources for the fundamental N5 and N4 points. It will definitely get less towards N3. I find myself skipping many of the extra reading bits now because the Bunpro explanation and example sentences suffice.
However, even though many of the more sophisticated grammar patterns are simply combinations of things I have seen before there is definitely a use to those further reading recommendations. Many of those patterns have similar meanings with different nuances.
For that reason I always make sure to read those resources that compare a few different grammar points and explore their nuances. (Usually there is like a StackExchange post or Bunpro forum post linked that compares them if that is applicable).
However I think some of the linked resources can be a bit too much to process at once if all you want is to get a basic grasp of the grammar.
Like what you described about spending an hour on learning what です means, plus more technical jargon, that sounds a bit like Imabi. And while I like Imabi for it’s depth and deep background explanations, I don’t think it is the most suitable for quickly getting started.
Judging what is too much information is difficult for a beginner and everybody learns slightly differently. But one thing is clear: if you spend too much time reading dry grammar resources and don’t get enough results to get your dopamine flowing you are more likely to get frustrated and quit.
So my recommendation: read those resouces that focus mostly on teaching you how to interpret and use a grammar point (like Tae Kim or Maggie sensei’s guides, among others), then move on and see how you are doing in practice. You can always come back to the more elaborate resources later.
Oh and about the technical jargon: it is useful to at least have a basic grasp on the most common terms. You don’t need to become a scientist for this. Many of these concepts are fairly simple to understand, at least for our purposes. If the explanation for a term reads more like a Wikipedia article then you should probably go find a different explanation.