I can get on board with 99% of that as being stuff a style guide can reasonably standardize for organizational voice, but the one thing that doesn't sit well with me is preferring "in to" over "into" in the second example at the end: "Learn how to sign in to Power BI" seems like it wants to use "into" for the same reason we would use that compound word any other time it should be used.

"sign in" is a verbal phrase. You can't merge "in" with "to" without losing its meaning.

Perhaps my grammer isn't as sharp as it should be, but I don't understand how "go in" would be any different. We say "please go in" and "please go into the room" without any issues, I think. What is fundamentally different between "sign in" and "go in" leading to this style guide not also discouraging "go into?"

I don't interpret a meaningful difference between "can not" and "cannot," nor between "any more" and "anymore;" thus, I don't find a meaningful difference between "in to" and "into."