Create entire levels and export them?

New to Blender, so I have a long road ahead. What is the best way or is there a tutorial out there (I’ve been searching, but haven’t found exactly what I need…stating exactly, because I need step by step instructions) to take my pixel png images uv map them as textures to a 3D model and lay everything out as a video game level and export entire scene as a level to a program like Unity?

For more clarification I have a 1280x240 pixel size ground of grass and dirt I need to put on a 3D model or plane for the player to walk on in a beat em up world like a Double Dragon game.

Is there a way in Blender to create that size plane or 3D model of sorts and just draw pixel art on it or could I just import 64x64 pieces and snap them together?

Then I have a backdrop of 1280x240 of a city background that can stay 2D, but needs a box collider around it so the player doesn’t go through it…obviously it will be placed just behind the 3D model/ground.

Suggestions for for someone very new to this? Thank you for your time.