Tilemap sprite width and height, and blurry effect on pixel art sprites on mobile phone

Hi.
I am making a 2D game, with sprites which are 32 pixels width by 16 pixels height. I use these pixel art sprites, in order to build my Tilemaps. In most examples, I have seen on internet, or into Unity Learning, or Purchased Tutos, the tiles are always squares (width = height = power(2,n)). I have found a trick to make my Tilemaps with my rectangle sprites, using the properties of the grid. Cell size : X = 2, Y=1, Z=0, and this works fine.

You can have a look in the Github repo specified below.

But first, I want to be sure that, this is not mandatory that tiles must be squared, because in the explanations I have read, Pixel Per Unit is relative to the height of a sprite. There is no other parameter for the width.

After, I am completely stuck because my target platform for my game is mobile phone, and my maps, or my player are blurry and I do not know how to keep pixel perfect with different screen sizes and aspect ratios. I have read that there are things to tune with my camera settings, but honestly, this does not work or I do not understand how to make it work.

I really need help or a good tuto on pixel perfect and Tilemap for Mobile Phone games.

Many thanks.

https://github.com/CheyenneEphemere/Gods/tree/master/Gods/Assets/Sprites

~Cheyenne