How to write my own shaders

I want to learn how to create my own shaders. I would like to use shader graph, but I'm working on a project that was created in the non-scriptable render pipeline and it would be hard to switch to HDRP or URP. I tried to upgrade, but the entire project was ruined. I made a copy so the project is safe. Where I can find tutorials on shaders in unity because there are very few and I think this is because most of users are using shader graph, and I used unity in 2016 when shader graph wasn't even a concept for unity and even in 2016 most of the users tried to use already existing shaders. I find shader writting very confusing. In the scripting of the actual game using c# I'm feeling comfortable, but the shader scripting is very weird and non-intuitive unlike writing c# scripts for the game. Reply with tutorials and websites where I can learn shaders not assetstore links with assets like amplify shader because I know there are visual shader scripting solution for non-scriptable render pipeline but if I can't use shader graph I would like to write my own shader.

 

Catlike coding is a great resource.

https://catlikecoding.com/unity/tutorials/scriptable-render-pipeline/custom-shaders/

Also lots of stuff on youtube if you search for custom unity shader.