So the knife tool solution seems alright, but I didn’t want to
A) do that manually (I’m lazy) and
B) add extra topology I might need to maintain (I’m lazy).
So I set out to look for other solutions to the shading problem, which in my case was quite severe.
Now one immediate solution I could think of was using Inset. It was much less manual labor, just select the faces you want and inset over them and you get roughly the same result as with the knife tool. This adds extra topology though, so doesn’t work for point B)
Is there maybe some sort of inset modifier? A quick google search tells me that there is a suggestion of adding an inset modifier, alas it’s only a suggestion and not a feature in Blender.
However, there IS a Bevel modifier! And it’s working decently well too:
Pros:
Solves the problem
Doesn’t add new topology to maintain (but does add like 300 quads to render)
Is non-destructive
Can be adjusted whenever
Has the Shading > Harden Normals option which gives excellent result with even just 1 bevel-segment (minimizes the need for additional rendering topology)
At the same time, you can choose to have little bit of roundness around the edges, it is a bevel after all, or if you don’t like that you can set it to 0.0001m for those sharp edges.
Cons:
Adds like 300 quads