How do I make a custom renderer?

I tried using a render pipeline but it was too strict for what I needed to do. Is there a way to completely override the game/scene view and draw every pixel by myself?

Note: I still want to use the GPU

This is the design principle behind Scriptable Render Pipelines; allowing lower level control over the full rendering process. Catlike Coding has a great series on writing a custom SRP;

Just be aware that it isn’t as simple as just ‘make a custom renderer’ - you will have to manually implement any feature you want (object drawing, lighting, shadows, reflections, PBR, post-processing, etc.)