Pixelization creates artifacts with outline - Post Process

Hello my friends!
What am I trying to achieve is a post process that would simulate look of Pokemon games on N3ds.

As you can see, characters there have one-pixel wide outline. The whole image is Pixelized because of 3ds’s low resolution.

I could simply achieve simmilar effect by setting low resolution scale and adding outline effect from “Stylized Rendering” Project. But unfortunately that way executes with quite blurry image.
That is why I’ve decided to create my own post process blendable that would pixelate my game.

Here is my simple pixelization:

Unfortunately, this two post processes dosn’t work well with each other. There are places, where outline is 2 pixel wide, and there are where there isnt any outline although it should be.

Does somebody know how to avoid those artiffacts?
My guess is, that some values, should be ceiled instead of floored. But i have totally no idea how to get those values, and how to execute all those calculations within material editor.
If You’ve read all of this, thank you for Your attention.

PS. Maybe there is some other way to achieve look of low-res game with 1pixel wide outline. If you know, please tell me.

I’m pretty sure the pixelation is caused by the render resolution, not shader work. If you look at these images I took of Citra, a 3ds emulator. The first one is of native resolution, and the second is with 3x resolution. With the resolution increase we get smoother lines.

Taking this to Unreal Engine, I can play with the scalability settings to get a similar effect. Turning AA to Low (OFF), setting the render resolution to 33%, and halving the line thickness in the material instance for the outline post-process, I can get a similar effect.

Obviously, this isn’t perfect and is kinda weird, and my outline shader isn’t the best either. It’s probably possible to achieve a really similar effect with some tweaking and work though. I ended up coming across this thread cause I wanted to achieve a similar effect, hope this helps though.