Setting the view quality to Nearest Neigbour does not affect layer scaling. Also, it's impossible to create non-aliased text with AP without a proper nearest neighbour mode. Raserizing a pixelart image layer smooths it to oblivion, so unfortunately in its current state it's not possible to work with pixel art layers and text in Affinity (Pixelate filter is not viable since it doesn't remove the aliased pixels which ruins pixel art).
An example included, with
1. Original sprite
2. Scaled up with yucky aliasing
3. Horrible mush when rasterizing layer